| Arizona Plants Checklist 2008 | |||
| Data Source: USDA, NRCS. 2008. The PLANTS Database (http://plants.usda.gov, 3 February 2008).
National Plant Data Center, Baton Rouge, LA 70874-4490 USA. |
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| Scientific Name | Common Name | Family | |
| A | |||
| Abies | fir | Pinaceae | |
| Abies concolor | white fir | Pinaceae | |
| Abies concolor var. concolor | white fir | Pinaceae | |
| Abies lasiocarpa | subalpine fir | Pinaceae | |
| Abies lasiocarpa var. arizonica | corkbark fir | Pinaceae | |
| Abies lasiocarpa var. lasiocarpa | subalpine fir | Pinaceae | |
| Abronia | sand verbena | Nyctaginaceae | |
| Abronia angustifolia | purple sand verbena | Nyctaginaceae | |
| Abronia elliptica | fragrant white sand verbena | Nyctaginaceae | |
| Abronia fragrans | snowball sand verbena | Nyctaginaceae | |
| Abronia nana | dwarf sand verbena | Nyctaginaceae | |
| Abronia nana var. nana | dwarf sand verbena | Nyctaginaceae | |
| Abronia villosa | desert sand verbena | Nyctaginaceae | |
| Abronia villosa var. aurita | desert sand verbena | Nyctaginaceae | |
| Abronia villosa var. villosa | desert sand verbena | Nyctaginaceae | |
| Abutilon | Indian mallow | Malvaceae | |
| Abutilon abutiloides | shrubby Indian mallow | Malvaceae | |
| Abutilon incanum | pelotazo | Malvaceae | |
| Abutilon malacum | yellow Indian mallow | Malvaceae | |
| Abutilon mollicomum | Sonoran Indian mallow | Malvaceae | |
| Abutilon palmeri | Palmer's Indian mallow | Malvaceae | |
| Abutilon parishii | Parish's Indian mallow | Malvaceae | |
| Abutilon parvulum | dwarf Indian mallow | Malvaceae | |
| Abutilon reventum | yellowflower Indian mallow | Malvaceae | |
| Abutilon theophrasti | velvetleaf | Malvaceae | |
| Abutilon thurberi | Thurber's Indian mallow | Malvaceae | |
| Acacia | acacia | Fabaceae | |
| Acacia angustissima | prairie acacia | Fabaceae | |
| Acacia angustissima var. shrevei | Shreve's prairie acacia | Fabaceae | |
| Acacia angustissima var. suffrutescens | prairie acacia | Fabaceae | |
| Acacia angustissima var. texensis | prairie wattle | Fabaceae | |
| Acacia constricta | whitethorn acacia | Fabaceae | |
| Acacia constricta var. constricta | whitethorn acacia | Fabaceae | |
| Acacia constricta var. paucispina | whitethorn acacia | Fabaceae | |
| Acacia farnesiana | sweet acacia | Fabaceae | |
| Acacia greggii | catclaw acacia | Fabaceae | |
| Acacia greggii var. greggii | catclaw acacia | Fabaceae | |
| Acacia millefolia | milfoil wattle | Fabaceae | |
| Acacia neovernicosa | viscid acacia | Fabaceae | |
| Acacia redolens | bank catclaw | Fabaceae | |
| Acalypha | copperleaf | Euphorbiaceae | |
| Acalypha californica | California copperleaf | Euphorbiaceae | |
| Acalypha mexicana | Mexican copperleaf | Euphorbiaceae | |
| Acalypha neomexicana | New Mexico copperleaf | Euphorbiaceae | |
| Acalypha ostryifolia | pineland threeseed mercury | Euphorbiaceae | |
| Acalypha phleoides | shrubby copperleaf | Euphorbiaceae | |
| Acamptopappus | goldenhead | Asteraceae | |
| Acamptopappus sphaerocephalus | rayless goldenhead | Asteraceae | |
| Acamptopappus sphaerocephalus var. hirtellus | rayless goldenhead | Asteraceae | |
| Acamptopappus sphaerocephalus var. sphaerocephalus | rayless goldenhead | Asteraceae | |
| Acer | maple | Aceraceae | |
| Acer glabrum | Rocky Mountain maple | Aceraceae | |
| Acer glabrum var. diffusum | Rocky Mountain maple | Aceraceae | |
| Acer glabrum var. glabrum | Rocky Mountain maple | Aceraceae | |
| Acer glabrum var. neomexicanum | New Mexico maple | Aceraceae | |
| Acer grandidentatum | bigtooth maple | Aceraceae | |
| Acer grandidentatum var. grandidentatum | bigtooth maple | Aceraceae | |
| Acer grandidentatum var. sinuosum | canyon maple | Aceraceae | |
| Acer negundo | boxelder | Aceraceae | |
| Acer negundo var. arizonicum | Arizona boxelder | Aceraceae | |
| Acer negundo var. interius | boxelder | Aceraceae | |
| Achillea | yarrow | Asteraceae | |
| Achillea millefolium | common yarrow | Asteraceae | |
| Achillea millefolium var. alpicola | common yarrow | Asteraceae | |
| Achillea millefolium var. occidentalis | western yarrow | Asteraceae | |
| Achnatherum | needlegrass | Poaceae | |
| Achnatherum aridum | Mormon needlegrass | Poaceae | |
| Achnatherum bloomeri | Poaceae | ||
| Achnatherum eminens | southwestern needlegrass | Poaceae | |
| Achnatherum hymenoides | Indian ricegrass | Poaceae | |
| Achnatherum lemmonii | Lemmon's needlegrass | Poaceae | |
| Achnatherum lemmonii var. lemmonii | Lemmon's needlegrass | Poaceae | |
| Achnatherum lettermanii | Letterman's needlegrass | Poaceae | |
| Achnatherum lobatum | littleawn needlegrass | Poaceae | |
| Achnatherum nelsonii | Columbia needlegrass | Poaceae | |
| Achnatherum nelsonii ssp. dorei | Dore's needlegrass | Poaceae | |
| Achnatherum nelsonii ssp. nelsonii | Columbia needlegrass | Poaceae | |
| Achnatherum occidentale | western needlegrass | Poaceae | |
| Achnatherum occidentale ssp. pubescens | pubescent western needlegrass | Poaceae | |
| Achnatherum parishii | Parish's needlegrass | Poaceae | |
| Achnatherum parishii var. parishii | Parish's needlegrass | Poaceae | |
| Achnatherum perplexum | New Mexico needlegrass | Poaceae | |
| Achnatherum pinetorum | pine needlegrass | Poaceae | |
| Achnatherum robustum | sleepygrass | Poaceae | |
| Achnatherum speciosum | desert needlegrass | Poaceae | |
| Achyronychia | achyronychia | Caryophyllaceae | |
| Achyronychia cooperi | onyxflower | Caryophyllaceae | |
| Acleisanthes | trumpets | Nyctaginaceae | |
| Acleisanthes longiflora | angel's trumpets | Nyctaginaceae | |
| Aconitum | monkshood | Ranunculaceae | |
| Aconitum columbianum | Columbian monkshood | Ranunculaceae | |
| Aconitum columbianum ssp. columbianum | Columbian monkshood | Ranunculaceae | |
| Aconitum infectum | Arizona monkshood | Ranunculaceae | |
| Acourtia | desertpeony | Asteraceae | |
| Acourtia nana | dwarf desertpeony | Asteraceae | |
| Acourtia thurberi | Thurber's desertpeony | Asteraceae | |
| Acourtia wrightii | brownfoot | Asteraceae | |
| Acroptilon | hardheads | Asteraceae | |
| Acroptilon repens | hardheads | Asteraceae | |
| Actaea | baneberry | Ranunculaceae | |
| Actaea arizonica | Arizona bugbane | Ranunculaceae | |
| Actaea rubra | red baneberry | Ranunculaceae | |
| Actaea rubra ssp. arguta | red baneberry | Ranunculaceae | |
| Adenophyllum | dogweed | Asteraceae | |
| Adenophyllum cooperi | Cooper's dogweed | Asteraceae | |
| Adenophyllum porophylloides | San Felipe dogweed | Asteraceae | |
| Adenophyllum porophyllum | poreleaf dogweed | Asteraceae | |
| Adenophyllum wrightii | Wright's dogweed | Asteraceae | |
| Adiantum | maidenhair fern | Pteridaceae | |
| Adiantum aleuticum | Aleutian maidenhair | Pteridaceae | |
| Adiantum capillus-veneris | common maidenhair | Pteridaceae | |
| Aegilops | goatgrass | Poaceae | |
| Aegilops cylindrica | jointed goatgrass | Poaceae | |
| Aegilops tauschii | Tausch's goatgrass | Poaceae | |
| Aegopogon | relaxgrass | Poaceae | |
| Aegopogon tenellus | fragilegrass | Poaceae | |
| Aeluropus | Poaceae | ||
| Aeluropus littoralis | Poaceae | ||
| Aeschynomene | jointvetch | Fabaceae | |
| Aeschynomene villosa | hairy jointvetch | Fabaceae | |
| Agastache | giant hyssop | Lamiaceae | |
| Agastache breviflora | Trans-Pecos giant hyssop | Lamiaceae | |
| Agastache micrantha | white giant hyssop | Lamiaceae | |
| Agastache pallida | pale giant hyssop | Lamiaceae | |
| Agastache pallidiflora | Bill Williams Mountain giant hyssop | Lamiaceae | |
| Agastache pallidiflora ssp. pallidiflora | Bill Williams Mountain giant hyssop | Lamiaceae | |
| Agastache pallidiflora ssp. pallidiflora var. gilensis | Bill Williams Mountain giant hyssop | Lamiaceae | |
| Agastache pallidiflora ssp. pallidiflora var. greenei | Bill Williams Mountain giant hyssop | Lamiaceae | |
| Agastache pallidiflora ssp. pallidiflora var. pallidiflora | Bill Williams Mountain giant hyssop | Lamiaceae | |
| Agastache rupestris | threadleaf giant hyssop | Lamiaceae | |
| Agastache wrightii | Sonoran giant hyssop | Lamiaceae | |
| Agave | agave | Agavaceae | |
| Agave ajoensis | Agavaceae | ||
| Agave americana | American century plant | Agavaceae | |
| Agave americana ssp. americana | American century plant | Agavaceae | |
| Agave americana ssp. americana var. expansa | American century plant | Agavaceae | |
| Agave arizonica | Arizona century plant | Agavaceae | |
| Agave chrysantha | goldenflower century plant | Agavaceae | |
| Agave delamateri | Tonto Basin century plant | Agavaceae | |
| Agave deserti | desert agave | Agavaceae | |
| Agave deserti ssp. simplex | desert agave | Agavaceae | |
| Agave murpheyi | Murphey's century plant | Agavaceae | |
| Agave palmeri | Palmer's century plant | Agavaceae | |
| Agave parryi | Parry's agave | Agavaceae | |
| Agave parryi ssp. parryi | Parry's agave | Agavaceae | |
| Agave parviflora | smallflower century plant | Agavaceae | |
| Agave phillipsiana | Grand Canyon century plant | Agavaceae | |
| Agave schottii | Schott's century plant | Agavaceae | |
| Agave schottii var. schottii | Schott's century plant | Agavaceae | |
| Agave schottii var. treleasei | Trelease's century plant | Agavaceae | |
| Agave toumeyana | Toumey's century plant | Agavaceae | |
| Agave toumeyana var. bella | Toumey's century plant | Agavaceae | |
| Agave toumeyana var. toumeyana | Toumey's century plant | Agavaceae | |
| Agave univittata | McKelvey's century plant | Agavaceae | |
| Agave utahensis | Utah agave | Agavaceae | |
| Agave utahensis var. kaibabensis | Kaibab agave | Agavaceae | |
| Agave utahensis var. utahensis | Utah agave | Agavaceae | |
| Ageratina | snakeroot | Asteraceae | |
| Ageratina herbacea | fragrant snakeroot | Asteraceae | |
| Ageratina lemmonii | Lemmon's snakeroot | Asteraceae | |
| Ageratina paupercula | Santa Rita snakeroot | Asteraceae | |
| Ageratina rothrockii | Rothrock's snakeroot | Asteraceae | |
| Ageratina wrightii | Wright's snakeroot | Asteraceae | |
| Ageratum | whiteweed | Asteraceae | |
| Ageratum corymbosum | flat-top whiteweed | Asteraceae | |
| Agoseris | agoseris | Asteraceae | |
| Agoseris aurantiaca | orange agoseris | Asteraceae | |
| Agoseris aurantiaca var. purpurea | orange agoseris | Asteraceae | |
| Agoseris glauca | pale agoseris | Asteraceae | |
| Agoseris glauca var. dasycephala | pale agoseris | Asteraceae | |
| Agoseris glauca var. glauca | pale agoseris | Asteraceae | |
| Agoseris glauca var. laciniata | false agoseris | Asteraceae | |
| Agoseris heterophylla | annual agoseris | Asteraceae | |
| Agoseris heterophylla var. heterophylla | annual agoseris | Asteraceae | |
| Agrimonia | agrimony | Rosaceae | |
| Agrimonia gryposepala | tall hairy agrimony | Rosaceae | |
| Agrimonia striata | roadside agrimony | Rosaceae | |
| Agropyron | wheatgrass | Poaceae | |
| Agropyron desertorum | desert wheatgrass | Poaceae | |
| Agrostis | bentgrass | Poaceae | |
| Agrostis elliottiana | Elliott's bentgrass | Poaceae | |
| Agrostis exarata | spike bentgrass | Poaceae | |
| Agrostis gigantea | redtop | Poaceae | |
| Agrostis idahoensis | Idaho bentgrass | Poaceae | |
| Agrostis scabra | rough bentgrass | Poaceae | |
| Agrostis stolonifera | creeping bentgrass | Poaceae | |
| Ailanthus | ailanthus | Simaroubaceae | |
| Ailanthus altissima | tree of heaven | Simaroubaceae | |
| Albizia | albizia | Fabaceae | |
| Albizia julibrissin | silktree | Fabaceae | |
| Aletes | Indian parsley | Apiaceae | |
| Aletes macdougalii | MacDougal's Indian parsley | Apiaceae | |
| Aletes macdougalii ssp. macdougalii | MacDougal's Indian parsley | Apiaceae | |
| Aletes sessiliflorus | sessileflower Indian parsley | Apiaceae | |
| Alhagi | alhagi | Fabaceae | |
| Alhagi maurorum | camelthorn | Fabaceae | |
| Aliciella | Polemoniaceae | ||
| Aliciella hutchinsifolia | desert pale gilia | Polemoniaceae | |
| Aliciella latifolia | broad-leaf gilia | Polemoniaceae | |
| Aliciella latifolia ssp. latifolia | broadleaf gilia | Polemoniaceae | |
| Aliciella leptomeria | sand gilia | Polemoniaceae | |
| Aliciella lottiae | Lott's gilia | Polemoniaceae | |
| Aliciella subacaulis | pinyon gilia | Polemoniaceae | |
| Aliciella subnuda | coral gilia | Polemoniaceae | |
| Aliciella triodon | coyote gilia | Polemoniaceae | |
| Alisma | water plantain | Alismataceae | |
| Alisma gramineum | narrowleaf water plantain | Alismataceae | |
| Alisma subcordatum | American water plantain | Alismataceae | |
| Alisma triviale | northern water plantain | Alismataceae | |
| Allenrolfea | allenrolfea | Chenopodiaceae | |
| Allenrolfea occidentalis | iodinebush | Chenopodiaceae | |
| Allionia | windmills | Nyctaginaceae | |
| Allionia choisyi | annual windmills | Nyctaginaceae | |
| Allionia incarnata | trailing windmills | Nyctaginaceae | |
| Allionia incarnata var. incarnata | trailing windmills | Nyctaginaceae | |
| Allionia incarnata var. nudata | trailing windmills | Nyctaginaceae | |
| Allionia incarnata var. villosa | trailing windmills | Nyctaginaceae | |
| Allium | onion | Liliaceae | |
| Allium acuminatum | tapertip onion | Liliaceae | |
| Allium atrorubens | darkred onion | Liliaceae | |
| Allium atrorubens var. atrorubens | darkred onion | Liliaceae | |
| Allium atrorubens var. cristatum | darkred onion | Liliaceae | |
| Allium bigelovii | Bigelow's onion | Liliaceae | |
| Allium bisceptrum | twincrest onion | Liliaceae | |
| Allium bisceptrum var. palmeri | aspen onion | Liliaceae | |
| Allium cernuum | nodding onion | Liliaceae | |
| Allium cernuum var. neomexicanum | New Mexican nodding onion | Liliaceae | |
| Allium cernuum var. obtusum | nodding onion | Liliaceae | |
| Allium geyeri | Geyer's onion | Liliaceae | |
| Allium geyeri var. geyeri | Geyer's onion | Liliaceae | |
| Allium geyeri var. tenerum | bulbil onion | Liliaceae | |
| Allium glandulosum | gland onion | Liliaceae | |
| Allium gooddingii | Goodding's onion | Liliaceae | |
| Allium kunthii | Kunth's onion | Liliaceae | |
| Allium macropetalum | largeflower onion | Liliaceae | |
| Allium nevadense | Nevada onion | Liliaceae | |
| Allium parishii | Parish's onion | Liliaceae | |
| Allium plummerae | Tanners Canyon onion | Liliaceae | |
| Allophyllum | false gilyflower | Polemoniaceae | |
| Allophyllum gilioides | dense false gilyflower | Polemoniaceae | |
| Allophyllum gilioides ssp. gilioides | dense false gilyflower | Polemoniaceae | |
| Almutaster | alkali marsh aster | Asteraceae | |
| Almutaster pauciflorus | alkali marsh aster | Asteraceae | |
| Alnus | alder | Betulaceae | |
| Alnus incana | gray alder | Betulaceae | |
| Alnus incana ssp. tenuifolia | thinleaf alder | Betulaceae | |
| Alnus oblongifolia | Arizona alder | Betulaceae | |
| Alopecurus | foxtail | Poaceae | |
| Alopecurus aequalis | shortawn foxtail | Poaceae | |
| Alopecurus aequalis var. aequalis | shortawn foxtail | Poaceae | |
| Alopecurus arundinaceus | creeping meadow foxtail | Poaceae | |
| Alopecurus carolinianus | Carolina foxtail | Poaceae | |
| Alopecurus geniculatus | water foxtail | Poaceae | |
| Alopecurus geniculatus var. geniculatus | water foxtail | Poaceae | |
| Aloysia | beebrush | Verbenaceae | |
| Aloysia gratissima | whitebrush | Verbenaceae | |
| Aloysia gratissima var. schulziae | whitebrush | Verbenaceae | |
| Aloysia wrightii | Wright's beebrush | Verbenaceae | |
| Alternanthera | joyweed | Amaranthaceae | |
| Alternanthera caracasana | washerwoman | Amaranthaceae | |
| Amaranthus | pigweed | Amaranthaceae | |
| Amaranthus acanthochiton | greenstripe | Amaranthaceae | |
| Amaranthus albus | prostrate pigweed | Amaranthaceae | |
| Amaranthus blitoides | mat amaranth | Amaranthaceae | |
| Amaranthus caudatus | love-lies-bleeding | Amaranthaceae | |
| Amaranthus crassipes | spreading amaranth | Amaranthaceae | |
| Amaranthus crassipes var. crassipes | spreading amaranth | Amaranthaceae | |
| Amaranthus cruentus | red amaranth | Amaranthaceae | |
| Amaranthus fimbriatus | fringed amaranth | Amaranthaceae | |
| Amaranthus hybridus | slim amaranth | Amaranthaceae | |
| Amaranthus hypochondriacus | Prince-of-Wales feather | Amaranthaceae | |
| Amaranthus obcordatus | Trans-Pecos amaranth | Amaranthaceae | |
| Amaranthus palmeri | carelessweed | Amaranthaceae | |
| Amaranthus powellii | Powell's amaranth | Amaranthaceae | |
| Amaranthus powellii ssp. powellii | Powell's amaranth | Amaranthaceae | |
| Amaranthus pringlei | Pringle's amaranth | Amaranthaceae | |
| Amaranthus retroflexus | redroot amaranth | Amaranthaceae | |
| Amaranthus torreyi | Torrey's amaranthus | Amaranthaceae | |
| Amaranthus tucsonensis | Amaranthaceae | ||
| Amaranthus venulosus | fringed amaranth | Amaranthaceae | |
| Amaranthus viridis | slender amaranth | Amaranthaceae | |
| Amaranthus watsonii | Watson's amaranth | Amaranthaceae | |
| Amaranthus wrightii | Wright's amaranth | Amaranthaceae | |
| Ambrosia | ragweed | Asteraceae | |
| Ambrosia acanthicarpa | flatspine bur ragweed | Asteraceae | |
| Ambrosia ambrosioides | ambrosia leaf bur ragweed | Asteraceae | |
| Ambrosia artemisiifolia | annual ragweed | Asteraceae | |
| Ambrosia artemisiifolia var. elatior | annual ragweed | Asteraceae | |
| Ambrosia canescens | hairy ragweed | Asteraceae | |
| Ambrosia confertiflora | weakleaf bur ragweed | Asteraceae | |
| Ambrosia cordifolia | Tucson bur ragweed | Asteraceae | |
| Ambrosia deltoidea | triangle bur ragweed | Asteraceae | |
| Ambrosia dumosa | burrobush | Asteraceae | |
| Ambrosia eriocentra | woolly fruit bur ragweed | Asteraceae | |
| Ambrosia ilicifolia | hollyleaf bur ragweed | Asteraceae | |
| Ambrosia psilostachya | Cuman ragweed | Asteraceae | |
| Ambrosia tomentosa | skeletonleaf bur ragweed | Asteraceae | |
| Ambrosia trifida | great ragweed | Asteraceae | |
| Ambrosia trifida var. texana | Texan great ragweed | Asteraceae | |
| Ambrosia trifida var. trifida | great ragweed | Asteraceae | |
| Amelanchier | serviceberry | Rosaceae | |
| Amelanchier pumila | dwarf serviceberry | Rosaceae | |
| Amelanchier utahensis | Utah serviceberry | Rosaceae | |
| Amelanchier utahensis var. covillei | Coville's serviceberry | Rosaceae | |
| Amelanchier utahensis var. utahensis | Utah serviceberry | Rosaceae | |
| Ammannia | redstem | Lythraceae | |
| Ammannia auriculata | eared redstem | Lythraceae | |
| Ammannia coccinea | valley redstem | Lythraceae | |
| Ammannia robusta | grand redstem | Lythraceae | |
| Ammi | ammi | Apiaceae | |
| Ammi majus | large bullwort | Apiaceae | |
| Ammocodon | ammocodon | Nyctaginaceae | |
| Ammocodon chenopodioides | goosefoot moonpod | Nyctaginaceae | |
| Ammoselinum | sandparsley | Apiaceae | |
| Ammoselinum giganteum | western sandparsley | Apiaceae | |
| Amoreuxia | yellowshow | Bixaceae | |
| Amoreuxia gonzalezii | Santa Rita mountain yellowshow | Bixaceae | |
| Amoreuxia palmatifida | Mexican yellowshow | Bixaceae | |
| Amorpha | false indigo | Fabaceae | |
| Amorpha californica | California false indigo | Fabaceae | |
| Amorpha californica var. californica | California false indigo | Fabaceae | |
| Amorpha fruticosa | desert false indigo | Fabaceae | |
| Amphipappus | chaffbush | Asteraceae | |
| Amphipappus fremontii | Fremont's chaffbush | Asteraceae | |
| Amphipappus fremontii ssp. spinosus | Fremont's chaffbush | Asteraceae | |
| Amsinckia | fiddleneck | Boraginaceae | |
| Amsinckia menziesii | Menzies' fiddleneck | Boraginaceae | |
| Amsinckia menziesii var. intermedia | common fiddleneck | Boraginaceae | |
| Amsinckia tessellata | bristly fiddleneck | Boraginaceae | |
| Amsinckia tessellata var. tessellata | bristly fiddleneck | Boraginaceae | |
| Amsonia | bluestar | Apocynaceae | |
| Amsonia grandiflora | Arizona bluestar | Apocynaceae | |
| Amsonia jonesii | Jones' bluestar | Apocynaceae | |
| Amsonia kearneyana | Kearney's bluestar | Apocynaceae | |
| Amsonia longiflora | tubular bluestar | Apocynaceae | |
| Amsonia longiflora var. longiflora | tubular bluestar | Apocynaceae | |
| Amsonia palmeri | Palmer's bluestar | Apocynaceae | |
| Amsonia peeblesii | Peebles' bluestar | Apocynaceae | |
| Amsonia tomentosa | woolly bluestar | Apocynaceae | |
| Amsonia tomentosa var. stenophylla | woolly bluestar | Apocynaceae | |
| Amsonia tomentosa var. tomentosa | woolly bluestar | Apocynaceae | |
| Anagallis | pimpernel | Primulaceae | |
| Anagallis arvensis | scarlet pimpernel | Primulaceae | |
| Anagallis arvensis ssp. arvensis | scarlet pimpernel | Primulaceae | |
| Anagallis minima | chaffweed | Primulaceae | |
| Anaphalis | pearly everlasting | Asteraceae | |
| Anaphalis margaritacea | western pearly everlasting | Asteraceae | |
| Andropogon | bluestem | Poaceae | |
| Andropogon gerardii | big bluestem | Poaceae | |
| Andropogon glomeratus | bushy bluestem | Poaceae | |
| Andropogon glomeratus var. pumilus | bushy bluestem | Poaceae | |
| Andropogon hallii | sand bluestem | Poaceae | |
| Androsace | rockjasmine | Primulaceae | |
| Androsace occidentalis | western rockjasmine | Primulaceae | |
| Androsace septentrionalis | pygmyflower rockjasmine | Primulaceae | |
| Androsace septentrionalis ssp. glandulosa | pygmyflower rockjasmine | Primulaceae | |
| Androsace septentrionalis ssp. puberulenta | pygmyflower rockjasmine | Primulaceae | |
| Androsace septentrionalis ssp. subulifera | pygmyflower rockjasmine | Primulaceae | |
| Androstephium | funnel lily | Liliaceae | |
| Androstephium breviflorum | pink funnel lily | Liliaceae | |
| Anemone | anemone | Ranunculaceae | |
| Anemone cylindrica | candle anemone | Ranunculaceae | |
| Anemone multifida | Pacific anemone | Ranunculaceae | |
| Anemone multifida var. multifida | Pacific anemone | Ranunculaceae | |
| Anemone multifida var. stylosa | Pacific anemone | Ranunculaceae | |
| Anemone tuberosa | tuber anemone | Ranunculaceae | |
| Anemone tuberosa var. tuberosa | tuber anemone | Ranunculaceae | |
| Anemopsis | yerba mansa | Saururaceae | |
| Anemopsis californica | yerba mansa | Saururaceae | |
| Anethum | dill | Apiaceae | |
| Anethum graveolens | dill | Apiaceae | |
| Angelica | angelica | Apiaceae | |
| Angelica pinnata | small-leaf angelica | Apiaceae | |
| Anisacanthus | desert honeysuckle | Acanthaceae | |
| Anisacanthus thurberi | Thurber's desert honeysuckle | Acanthaceae | |
| Anisocoma | anisocoma | Asteraceae | |
| Anisocoma acaulis | scalebud | Asteraceae | |
| Anoda | anoda | Malvaceae | |
| Anoda abutiloides | Indian anoda | Malvaceae | |
| Anoda crenatiflora | thicket anoda | Malvaceae | |
| Anoda cristata | crested anoda | Malvaceae | |
| Anoda lanceolata | lanceleaf anoda | Malvaceae | |
| Anoda pentaschista | field anoda | Malvaceae | |
| Anoda reticulata | netted anoda | Malvaceae | |
| Anoda thurberi | Arizona anoda | Malvaceae | |
| Antennaria | pussytoes | Asteraceae | |
| Antennaria marginata | whitemargin pussytoes | Asteraceae | |
| Antennaria media | Rocky Mountain pussytoes | Asteraceae | |
| Antennaria microphylla | littleleaf pussytoes | Asteraceae | |
| Antennaria parvifolia | small-leaf pussytoes | Asteraceae | |
| Antennaria rosea | rosy pussytoes | Asteraceae | |
| Antennaria rosea ssp. arida | rosy pussytoes | Asteraceae | |
| Antennaria rosea ssp. confinis | rosy pussytoes | Asteraceae | |
| Antennaria rosea ssp. pulvinata | pulvinate pussytoes | Asteraceae | |
| Antennaria rosulata | Kaibab pussytoes | Asteraceae | |
| Anthemis | chamomile | Asteraceae | |
| Anthemis cotula | stinking chamomile | Asteraceae | |
| Antheropeas | easterbonnets | Asteraceae | |
| Antheropeas lanosum | white easterbonnets | Asteraceae | |
| Antheropeas wallacei | woolly easterbonnets | Asteraceae | |
| Anthriscus | chervil | Apiaceae | |
| Anthriscus caucalis | bur chervil | Apiaceae | |
| Anulocaulis | ringstem | Nyctaginaceae | |
| Anulocaulis leiosolenus | southwestern ringstem | Nyctaginaceae | |
| Anulocaulis leiosolenus var. leiosolenus | southwestern ringstem | Nyctaginaceae | |
| Apacheria | apacheria | Crossosomataceae | |
| Apacheria chiricahuensis | apachebush | Crossosomataceae | |
| Apera | silkybent | Poaceae | |
| Apera interrupta | dense silkybent | Poaceae | |
| Aphanostephus | dozedaisy | Asteraceae | |
| Aphanostephus ramosissimus | plains dozedaisy | Asteraceae | |
| Aphanostephus ramosissimus var. humilis | plains dozedaisy | Asteraceae | |
| Apiastrum | apiastrum | Apiaceae | |
| Apiastrum angustifolium | mock parsley | Apiaceae | |
| Apium | celery | Apiaceae | |
| Apium graveolens | wild celery | Apiaceae | |
| Apium graveolens var. dulce | wild celery | Apiaceae | |
| Aplectrum | Adam and Eve | Orchidaceae | |
| Aplectrum hyemale | Adam and Eve | Orchidaceae | |
| Apocynum | dogbane | Apocynaceae | |
| Apocynum androsaemifolium | spreading dogbane | Apocynaceae | |
| Apocynum cannabinum | Indianhemp | Apocynaceae | |
| Apocynum floribundum | Apocynaceae | ||
| Apodanthera | apodanthera | Cucurbitaceae | |
| Apodanthera undulata | melon loco | Cucurbitaceae | |
| Aquilegia | columbine | Ranunculaceae | |
| Aquilegia chrysantha | golden columbine | Ranunculaceae | |
| Aquilegia chrysantha var. chrysantha | golden columbine | Ranunculaceae | |
| Aquilegia chrysantha var. rydbergii | Rydberg's golden columbine | Ranunculaceae | |
| Aquilegia coerulea | Colorado blue columbine | Ranunculaceae | |
| Aquilegia coerulea var. pinetorum | Colorado blue columbine | Ranunculaceae | |
| Aquilegia desertorum | desert columbine | Ranunculaceae | |
| Aquilegia elegantula | western red columbine | Ranunculaceae | |
| Aquilegia longissima | longspur columbine | Ranunculaceae | |
| Aquilegia micrantha | Mancos columbine | Ranunculaceae | |
| Aquilegia micrantha var. micrantha | Mancos columbine | Ranunculaceae | |
| Aquilegia triternata | Chiricahua Mountain columbine | Ranunculaceae | |
| Arabis | rockcress | Brassicaceae | |
| Arabis drummondii | Drummond's rockcress | Brassicaceae | |
| Arabis fendleri | Fendler's rockcress | Brassicaceae | |
| Arabis fendleri var. fendleri | Fendler's rockcress | Brassicaceae | |
| Arabis glabra | tower rockcress | Brassicaceae | |
| Arabis gracilipes | Flagstaff rockcress | Brassicaceae | |
| Arabis hirsuta | hairy rockcress | Brassicaceae | |
| Arabis hirsuta var. pycnocarpa | creamflower rockcress | Brassicaceae | |
| Arabis holboellii | Holboell's rockcress | Brassicaceae | |
| Arabis holboellii var. pinetorum | Holboell's rockcress | Brassicaceae | |
| Arabis lignifera | desert rockcress | Brassicaceae | |
| Arabis pendulina | rabbit ear rockcress | Brassicaceae | |
| Arabis pendulina var. pendulina | rabbit ear rockcress | Brassicaceae | |
| Arabis perennans | perennial rockcress | Brassicaceae | |
| Arabis pulchra | beautiful rockcress | Brassicaceae | |
| Arabis pulchra var. gracilis | beautiful rockcress | Brassicaceae | |
| Arabis pulchra var. pallens | beautiful rockcress | Brassicaceae | |
| Arabis sparsiflora | sicklepod rockcress | Brassicaceae | |
| Arabis sparsiflora var. sparsiflora | sicklepod rockcress | Brassicaceae | |
| Arabis tricornuta | Rincon Mountain rockcress | Brassicaceae | |
| Aralia | spikenard | Araliaceae | |
| Aralia humilis | Arizona spikenard | Araliaceae | |
| Aralia racemosa | American spikenard | Araliaceae | |
| Aralia racemosa ssp. bicrenata | American spikenard | Araliaceae | |
| Arbutus | madrone | Ericaceae | |
| Arbutus arizonica | Arizona madrone | Ericaceae | |
| Arceuthobium | dwarf mistletoe | Viscaceae | |
| Arceuthobium abietinum | fir dwarf mistletoe | Viscaceae | |
| Arceuthobium apachecum | Apache dwarf mistletoe | Viscaceae | |
| Arceuthobium blumeri | southwestern white pine dwarf mistletoe | Viscaceae | |
| Arceuthobium divaricatum | pinyon dwarf mistletoe | Viscaceae | |
| Arceuthobium douglasii | Douglas-fir dwarf mistletoe | Viscaceae | |
| Arceuthobium gillii | Huachuca Mountain dwarf mistletoe | Viscaceae | |
| Arceuthobium microcarpum | western spruce dwarf mistletoe | Viscaceae | |
| Arceuthobium vaginatum | pineland dwarf mistletoe | Viscaceae | |
| Arceuthobium vaginatum ssp. cryptopodum | pineland dwarf mistletoe | Viscaceae | |
| Arctium | burdock | Asteraceae | |
| Arctium minus | lesser burdock | Asteraceae | |
| Arctomecon | bearpoppy | Papaveraceae | |
| Arctomecon californica | California bearpoppy | Papaveraceae | |
| Arctostaphylos | manzanita | Ericaceae | |
| Arctostaphylos patula | greenleaf manzanita | Ericaceae | |
| Arctostaphylos pringlei | Pringle manzanita | Ericaceae | |
| Arctostaphylos pringlei ssp. pringlei | Pringle manzanita | Ericaceae | |
| Arctostaphylos pungens | pointleaf manzanita | Ericaceae | |
| Arctostaphylos uva-ursi | kinnikinnick | Ericaceae | |
| Arenaria | sandwort | Caryophyllaceae | |
| Arenaria aberrans | Mt. Dellenbaugh sandwort | Caryophyllaceae | |
| Arenaria aculeata | prickly sandwort | Caryophyllaceae | |
| Arenaria congesta | ballhead sandwort | Caryophyllaceae | |
| Arenaria congesta var. subcongesta | loosehead sandwort | Caryophyllaceae | |
| Arenaria eastwoodiae | Eastwood's sandwort | Caryophyllaceae | |
| Arenaria eastwoodiae var. adenophora | Eastwood's sandwort | Caryophyllaceae | |
| Arenaria eastwoodiae var. eastwoodiae | Eastwood's sandwort | Caryophyllaceae | |
| Arenaria fendleri | Fendler's sandwort | Caryophyllaceae | |
| Arenaria fendleri var. brevifolia | Fendler's sandwort | Caryophyllaceae | |
| Arenaria fendleri var. fendleri | Fendler's sandwort | Caryophyllaceae | |
| Arenaria fendleri var. porteri | Porter's sandwort | Caryophyllaceae | |
| Arenaria fendleri var. tweedyi | Tweedy's sandwort | Caryophyllaceae | |
| Arenaria lanuginosa | spreading sandwort | Caryophyllaceae | |
| Arenaria lanuginosa ssp. saxosa | spreading sandwort | Caryophyllaceae | |
| Arenaria macradenia | Mojave sandwort | Caryophyllaceae | |
| Arenaria macradenia ssp. ferrisiae | Ferris' sandwort | Caryophyllaceae | |
| Arenaria macradenia ssp. macradenia | Mojave sandwort | Caryophyllaceae | |
| Arenaria macradenia ssp. macradenia var. macradenia | Mojave sandwort | Caryophyllaceae | |
| Argemone | pricklypoppy | Papaveraceae | |
| Argemone arizonica | Arizona pricklypoppy | Papaveraceae | |
| Argemone corymbosa | Mojave pricklypoppy | Papaveraceae | |
| Argemone corymbosa ssp. arenicola | Mojave pricklypoppy | Papaveraceae | |
| Argemone corymbosa ssp. corymbosa | Mojave pricklypoppy | Papaveraceae | |
| Argemone gracilenta | Sonoran pricklypoppy | Papaveraceae | |
| Argemone munita | flatbud pricklypoppy | Papaveraceae | |
| Argemone munita ssp. argentea | flatbud pricklypoppy | Papaveraceae | |
| Argemone munita ssp. rotundata | flatbud pricklypoppy | Papaveraceae | |
| Argemone ochroleuca | pale Mexican pricklypoppy | Papaveraceae | |
| Argemone pleiacantha | southwestern pricklypoppy | Papaveraceae | |
| Argemone pleiacantha ssp. ambigua | southwestern pricklypoppy | Papaveraceae | |
| Argemone pleiacantha ssp. pleiacantha | southwestern pricklypoppy | Papaveraceae | |
| Argentina | silverweed | Rosaceae | |
| Argentina anserina | silverweed cinquefoil | Rosaceae | |
| Argyrochosma | false cloak fern | Pteridaceae | |
| Argyrochosma incana | hairy false cloak fern | Pteridaceae | |
| Argyrochosma jonesii | Jones' false cloak fern | Pteridaceae | |
| Argyrochosma limitanea | southwestern false cloak fern | Pteridaceae | |
| Argyrochosma limitanea ssp. limitanea | southwestern false cloak fern | Pteridaceae | |
| Argyrochosma limitanea ssp. mexicana | southwestern false cloak fern | Pteridaceae | |
| Argythamnia | silverbush | Euphorbiaceae | |
| Argythamnia adenophora | glandular silverbush | Euphorbiaceae | |
| Argythamnia brandegeei | Sonoran silverbush | Euphorbiaceae | |
| Argythamnia brandegeei var. intonsa | Sonoran silverbush | Euphorbiaceae | |
| Argythamnia claryana | desert silverbush | Euphorbiaceae | |
| Argythamnia cyanophylla | Charleston Mountain silverbush | Euphorbiaceae | |
| Argythamnia lanceolata | narrowleaf silverbush | Euphorbiaceae | |
| Argythamnia mercurialina | tall silverbush | Euphorbiaceae | |
| Argythamnia mercurialina var. mercurialina | tall silverbush | Euphorbiaceae | |
| Argythamnia neomexicana | New Mexico silverbush | Euphorbiaceae | |
| Argythamnia serrata | Yuma silverbush | Euphorbiaceae | |
| Aristida | threeawn | Poaceae | |
| Aristida adscensionis | sixweeks threeawn | Poaceae | |
| Aristida arizonica | Arizona threeawn | Poaceae | |
| Aristida californica | California threeawn | Poaceae | |
| Aristida californica var. californica | California threeawn | Poaceae | |
| Aristida californica var. glabrata | Santa Rita threeawn | Poaceae | |
| Aristida divaricata | poverty threeawn | Poaceae | |
| Aristida havardii | Havard's threeawn | Poaceae | |
| Aristida longespica | slimspike threeawn | Poaceae | |
| Aristida longespica var. longespica | slimspike threeawn | Poaceae | |
| Aristida oligantha | prairie threeawn | Poaceae | |
| Aristida pansa | Wooton's threeawn | Poaceae | |
| Aristida purpurea | purple threeawn | Poaceae | |
| Aristida purpurea var. fendleriana | Fendler's threeawn | Poaceae | |
| Aristida purpurea var. longiseta | Fendler threeawn | Poaceae | |
| Aristida purpurea var. nealleyi | blue threeawn | Poaceae | |
| Aristida purpurea var. parishii | Parish's threeawn | Poaceae | |
| Aristida purpurea var. perplexa | purple threeawn | Poaceae | |
| Aristida purpurea var. purpurea | purple threeawn | Poaceae | |
| Aristida purpurea var. wrightii | Wright's threeawn | Poaceae | |
| Aristida schiedeana | single threeawn | Poaceae | |
| Aristida schiedeana var. orcuttiana | Orcutt's threeawn | Poaceae | |
| Aristida ternipes | spidergrass | Poaceae | |
| Aristida ternipes var. gentilis | spidergrass | Poaceae | |
| Aristida ternipes var. ternipes | spidergrass | Poaceae | |
| Aristolochia | dutchman's pipe | Aristolochiaceae | |
| Aristolochia watsonii | Watson's dutchman's pipe | Aristolochiaceae | |
| Arnica | arnica | Asteraceae | |
| Arnica chamissonis | Chamisso arnica | Asteraceae | |
| Arnica chamissonis ssp. foliosa | Chamisso arnica | Asteraceae | |
| Arnica chamissonis ssp. foliosa var. andina | Chamisso arnica | Asteraceae | |
| Arnica cordifolia | heartleaf arnica | Asteraceae | |
| Arrhenatherum | oatgrass | Poaceae | |
| Arrhenatherum elatius | tall oatgrass | Poaceae | |
| Arrhenatherum elatius var. elatius | tall oatgrass | Poaceae | |
| Artemisia | sagebrush | Asteraceae | |
| Artemisia annua | sweet sagewort | Asteraceae | |
| Artemisia biennis | biennial wormwood | Asteraceae | |
| Artemisia biennis var. biennis | biennial wormwood | Asteraceae | |
| Artemisia bigelovii | Bigelow sage | Asteraceae | |
| Artemisia campestris | field sagewort | Asteraceae | |
| Artemisia campestris ssp. borealis | field sagewort | Asteraceae | |
| Artemisia campestris ssp. borealis var. scouleriana | field sagewort | Asteraceae | |
| Artemisia campestris ssp. caudata | field sagewort | Asteraceae | |
| Artemisia cana | silver sagebrush | Asteraceae | |
| Artemisia cana ssp. viscidula | silver sagebrush | Asteraceae | |
| Artemisia carruthii | Carruth's sagewort | Asteraceae | |
| Artemisia dracunculus | tarragon | Asteraceae | |
| Artemisia filifolia | sand sagebrush | Asteraceae | |
| Artemisia franserioides | ragweed sagebrush | Asteraceae | |
| Artemisia frigida | prairie sagewort | Asteraceae | |
| Artemisia lindleyana | Columbia River wormwood | Asteraceae | |
| Artemisia ludoviciana | white sagebrush | Asteraceae | |
| Artemisia ludoviciana ssp. albula | white sagebrush | Asteraceae | |
| Artemisia ludoviciana ssp. ludoviciana | white sagebrush | Asteraceae | |
| Artemisia ludoviciana ssp. mexicana | white sagebrush | Asteraceae | |
| Artemisia ludoviciana ssp. redolens | white sagebrush | Asteraceae | |
| Artemisia ludoviciana ssp. sulcata | white sagebrush | Asteraceae | |
| Artemisia nova | black sagebrush | Asteraceae | |
| Artemisia pygmaea | pygmy sagebrush | Asteraceae | |
| Artemisia tridentata | big sagebrush | Asteraceae | |
| Artemisia tridentata ssp. tridentata | basin big sagebrush | Asteraceae | |
| Artemisia tridentata ssp. wyomingensis | Wyoming big sagebrush | Asteraceae | |
| Arundo | giant reed | Poaceae | |
| Arundo donax | giant reed | Poaceae | |
| Asanthus | brickellbush | Asteraceae | |
| Asanthus squamulosus | Mule Mountain brickellbush | Asteraceae | |
| Asclepias | milkweed | Asclepiadaceae | |
| Asclepias albicans | whitestem milkweed | Asclepiadaceae | |
| Asclepias angustifolia | Arizona milkweed | Asclepiadaceae | |
| Asclepias asperula | spider milkweed | Asclepiadaceae | |
| Asclepias asperula ssp. asperula | spider milkweed | Asclepiadaceae | |
| Asclepias asperula ssp. capricornu | antelopehorns | Asclepiadaceae | |
| Asclepias brachystephana | bract milkweed | Asclepiadaceae | |
| Asclepias cryptoceras | pallid milkweed | Asclepiadaceae | |
| Asclepias cryptoceras ssp. cryptoceras | pallid milkweed | Asclepiadaceae | |
| Asclepias cutleri | Cutler's milkweed | Asclepiadaceae | |
| Asclepias engelmanniana | Engelmann's milkweed | Asclepiadaceae | |
| Asclepias erosa | desert milkweed | Asclepiadaceae | |
| Asclepias glaucescens | nodding milkweed | Asclepiadaceae | |
| Asclepias hallii | Hall's milkweed | Asclepiadaceae | |
| Asclepias hypoleuca | mahogany milkweed | Asclepiadaceae | |
| Asclepias involucrata | dwarf milkweed | Asclepiadaceae | |
| Asclepias latifolia | broadleaf milkweed | Asclepiadaceae | |
| Asclepias lemmonii | Lemmon's milkweed | Asclepiadaceae | |
| Asclepias linaria | pineneedle milkweed | Asclepiadaceae | |
| Asclepias macrotis | longhood milkweed | Asclepiadaceae | |
| Asclepias nummularia | tufted milkweed | Asclepiadaceae | |
| Asclepias nyctaginifolia | Mojave milkweed | Asclepiadaceae | |
| Asclepias quinquedentata | slimpod milkweed | Asclepiadaceae | |
| Asclepias rusbyi | Rusby's milkweed | Asclepiadaceae | |
| Asclepias speciosa | showy milkweed | Asclepiadaceae | |
| Asclepias subulata | rush milkweed | Asclepiadaceae | |
| Asclepias subverticillata | horsetail milkweed | Asclepiadaceae | |
| Asclepias tuberosa | butterfly milkweed | Asclepiadaceae | |
| Asclepias tuberosa ssp. interior | butterfly milkweed | Asclepiadaceae | |
| Asclepias uncialis | wheel milkweed | Asclepiadaceae | |
| Asclepias uncialis ssp. ruthiae | Ruth's milkweed | Asclepiadaceae | |
| Asclepias uncialis ssp. uncialis | wheel milkweed | Asclepiadaceae | |
| Asclepias verticillata | whorled milkweed | Asclepiadaceae | |
| Asclepias viridiflora | green comet milkweed | Asclepiadaceae | |
| Asclepias welshii | Welsh's milkweed | Asclepiadaceae | |
| Asparagus | asparagus | Liliaceae | |
| Asparagus officinalis | garden asparagus | Liliaceae | |
| Aspicarpa | asphead | Malpighiaceae | |
| Aspicarpa hirtella | chaparral asphead | Malpighiaceae | |
| Asplenium | spleenwort | Aspleniaceae | |
| Asplenium adiantum-nigrum | black spleenwort | Aspleniaceae | |
| Asplenium dalhousiae | Countess Dalhousie's spleenwort | Aspleniaceae | |
| Asplenium exiguum | little spleenwort | Aspleniaceae | |
| Asplenium monanthes | singlesorus spleenwort | Aspleniaceae | |
| Asplenium palmeri | Palmer's spleenwort | Aspleniaceae | |
| Asplenium platyneuron | ebony spleenwort | Aspleniaceae | |
| Asplenium platyneuron var. platyneuron | ebony spleenwort | Aspleniaceae | |
| Asplenium resiliens | blackstem spleenwort | Aspleniaceae | |
| Asplenium septentrionale | forked spleenwort | Aspleniaceae | |
| Asplenium trichomanes | maidenhair spleenwort | Aspleniaceae | |
| Asplenium trichomanes ssp. trichomanes | maidenhair spleenwort | Aspleniaceae | |
| Astragalus | milkvetch | Fabaceae | |
| Astragalus acutirostris | sharpkeel milkvetch | Fabaceae | |
| Astragalus albulus | cibola milkvetch | Fabaceae | |
| Astragalus allochrous | halfmoon milkvetch | Fabaceae | |
| Astragalus allochrous var. allochrous | halfmoon milkvetch | Fabaceae | |
| Astragalus allochrous var. playanus | halfmoon milkvetch | Fabaceae | |
| Astragalus amphioxys | Crescent milkvetch | Fabaceae | |
| Astragalus amphioxys var. amphioxys | Crescent milkvetch | Fabaceae | |
| Astragalus amphioxys var. modestus | Crescent milkvetch | Fabaceae | |
| Astragalus amphioxys var. musimonum | Crescent milkvetch | Fabaceae | |
| Astragalus amphioxys var. vespertinus | Aladdin's slippers | Fabaceae | |
| Astragalus ampullarius | gumbo milkvetch | Fabaceae | |
| Astragalus argophyllus | silverleaf milkvetch | Fabaceae | |
| Astragalus argophyllus var. martinii | silverleaf milkvetch | Fabaceae | |
| Astragalus argophyllus var. panguicensis | silverleaf milkvetch | Fabaceae | |
| Astragalus argophyllus var. stocksii | silverleaf milkvetch | Fabaceae | |
| Astragalus aridus | annual desert milkvetch | Fabaceae | |
| Astragalus arizonicus | Arizona milkvetch | Fabaceae | |
| Astragalus beathii | Beath's milkvetch | Fabaceae | |
| Astragalus bisulcatus | twogrooved milkvetch | Fabaceae | |
| Astragalus bisulcatus var. bisulcatus | twogrooved milkvetch | Fabaceae | |
| Astragalus bisulcatus var. haydenianus | Hayden's milkvetch | Fabaceae | |
| Astragalus bisulcatus var. major | twogrooved milkvetch | Fabaceae | |
| Astragalus brandegeei | Brandegee's milkvetch | Fabaceae | |
| Astragalus calycosus | Torrey's milkvetch | Fabaceae | |
| Astragalus calycosus var. calycosus | Torrey's milkvetch | Fabaceae | |
| Astragalus calycosus var. scaposus | Torrey's milkvetch | Fabaceae | |
| Astragalus castaneiformis | chestnut milkvetch | Fabaceae | |
| Astragalus ceramicus | painted milkvetch | Fabaceae | |
| Astragalus ceramicus var. ceramicus | painted milkvetch | Fabaceae | |
| Astragalus chuskanus | San Juan milkvetch | Fabaceae | |
| Astragalus cobrensis | copper mine milkvetch | Fabaceae | |
| Astragalus cobrensis var. cobrensis | copper mine milkvetch | Fabaceae | |
| Astragalus cobrensis var. maguirei | Maguire's milkvetch | Fabaceae | |
| Astragalus coccineus | scarlet milkvetch | Fabaceae | |
| Astragalus coltonii | Colton's milkvetch | Fabaceae | |
| Astragalus coltonii var. moabensis | Moab milkvetch | Fabaceae | |
| Astragalus crassicarpus | groundplum milkvetch | Fabaceae | |
| Astragalus crassicarpus var. cavus | groundplum milkvetch | Fabaceae | |
| Astragalus cremnophylax | sentry milkvetch | Fabaceae | |
| Astragalus cremnophylax var. cremnophylax | sentry milkvetch | Fabaceae | |
| Astragalus cremnophylax var. hevronii | sentry milkvetch | Fabaceae | |
| Astragalus cremnophylax var. myriorrhaphis | sentry milkvetch | Fabaceae | |
| Astragalus crotalariae | Salton milkvetch | Fabaceae | |
| Astragalus desperatus | rimrock milkvetch | Fabaceae | |
| Astragalus desperatus var. conspectus | rimrock milkvetch | Fabaceae | |
| Astragalus desperatus var. desperatus | rimrock milkvetch | Fabaceae | |
| Astragalus didymocarpus | dwarf white milkvetch | Fabaceae | |
| Astragalus didymocarpus var. dispermus | dwarf white milkvetch | Fabaceae | |
| Astragalus egglestonii | Eggleston's milkvetch | Fabaceae | |
| Astragalus emoryanus | Emory's milkvetch | Fabaceae | |
| Astragalus emoryanus var. emoryanus | Emory's milkvetch | Fabaceae | |
| Astragalus endopterus | sandbar milkvetch | Fabaceae | |
| Astragalus ensiformis | pagumpa milkvetch | Fabaceae | |
| Astragalus ensiformis var. ensiformis | pagumpa milkvetch | Fabaceae | |
| Astragalus episcopus | bishop's milkvetch | Fabaceae | |
| Astragalus episcopus var. episcopus | bishop's milkvetch | Fabaceae | |
| Astragalus episcopus var. lancearius | bishop's milkvetch | Fabaceae | |
| Astragalus eremiticus | hermit milkvetch | Fabaceae | |
| Astragalus eurylobus | Needle Mountain milkvetch | Fabaceae | |
| Astragalus flavus | yellow milkvetch | Fabaceae | |
| Astragalus flexuosus | flexile milkvetch | Fabaceae | |
| Astragalus flexuosus var. diehlii | Diehl's milkvetch | Fabaceae | |
| Astragalus flexuosus var. greenei | Greene's milkvetch | Fabaceae | |
| Astragalus fucatus | Hopi milkvetch | Fabaceae | |
| Astragalus geyeri | Geyer's milkvetch | Fabaceae | |
| Astragalus geyeri var. triquetrus | Geyer's milkvetch | Fabaceae | |
| Astragalus gilensis | Gila milkvetch | Fabaceae | |
| Astragalus hallii | Hall's milkvetch | Fabaceae | |
| Astragalus hallii var. fallax | Hall's milkvetch | Fabaceae | |
| Astragalus hartwegii | Hartweg's milkvetch | Fabaceae | |
| Astragalus holmgreniorum | Paradox milkvetch | Fabaceae | |
| Astragalus humistratus | groundcover milkvetch | Fabaceae | |
| Astragalus humistratus var. crispulus | groundcover milkvetch | Fabaceae | |
| Astragalus humistratus var. hosackiae | groundcover milkvetch | Fabaceae | |
| Astragalus humistratus var. humistratus | groundcover milkvetch | Fabaceae | |
| Astragalus humistratus var. humivagans | groundcover milkvetch | Fabaceae | |
| Astragalus humistratus var. sonorae | groundcover milkvetch | Fabaceae | |
| Astragalus humistratus var. tenerrimus | groundcover milkvetch | Fabaceae | |
| Astragalus hypoxylus | Huachuca Mountain milkvetch | Fabaceae | |
| Astragalus insularis | Cedros milkvetch | Fabaceae | |
| Astragalus insularis var. harwoodii | Harwood's milkvetch | Fabaceae | |
| Astragalus kentrophyta | spiny milkvetch | Fabaceae | |
| Astragalus kentrophyta var. coloradoensis | Colorado spiny milkvetch | Fabaceae | |
| Astragalus kentrophyta var. elatus | tall spiny milkvetch | Fabaceae | |
| Astragalus layneae | widow's milkvetch | Fabaceae | |
| Astragalus lentiginosus | freckled milkvetch | Fabaceae | |
| Astragalus lentiginosus var. ambiguus | freckled milkvetch | Fabaceae | |
| Astragalus lentiginosus var. australis | freckled milkvetch | Fabaceae | |
| Astragalus lentiginosus var. borreganus | Borrego milkvetch | Fabaceae | |
| Astragalus lentiginosus var. diphysus | freckled milkvetch | Fabaceae | |
| Astragalus lentiginosus var. maricopae | Maricopa milkvetch | Fabaceae | |
| Astragalus lentiginosus var. oropedii | freckled milkvetch | Fabaceae | |
| Astragalus lentiginosus var. palans | freckled milkvetch | Fabaceae | |
| Astragalus lentiginosus var. stramineus | freckled milkvetch | Fabaceae | |
| Astragalus lentiginosus var. trumbullensis | Fabaceae | ||
| Astragalus lentiginosus var. vitreus | freckled milkvetch | Fabaceae | |
| Astragalus lentiginosus var. wilsonii | Wilson's milkvetch | Fabaceae | |
| Astragalus lentiginosus var. yuccanus | yucca milkvetch | Fabaceae | |
| Astragalus lonchocarpus | rushy milkvetch | Fabaceae | |
| Astragalus magdalenae | satiny milkvetch | Fabaceae | |
| Astragalus magdalenae var. peirsonii | Peirson's milkvetch | Fabaceae | |
| Astragalus miser | timber milkvetch | Fabaceae | |
| Astragalus miser var. oblongifolius | timber milkvetch | Fabaceae | |
| Astragalus moencoppensis | Moenkopi milkvetch | Fabaceae | |
| Astragalus mokiacensis | Mokiak milkvetch | Fabaceae | |
| Astragalus mollissimus | woolly locoweed | Fabaceae | |
| Astragalus mollissimus var. bigelovii | woolly locoweed | Fabaceae | |
| Astragalus mollissimus var. mogollonicus | woolly locoweed | Fabaceae | |
| Astragalus mollissimus var. thompsoniae | woolly locoweed | Fabaceae | |
| Astragalus monumentalis | Monument Valley milkvetch | Fabaceae | |
| Astragalus monumentalis var. cottamii | Cottam's milkvetch | Fabaceae | |
| Astragalus monumentalis var. monumentalis | Monument Valley milkvetch | Fabaceae | |
| Astragalus newberryi | Newberry's milkvetch | Fabaceae | |
| Astragalus newberryi var. aquarii | Newberry's milkvetch | Fabaceae | |
| Astragalus newberryi var. blyae | Newberry's milkvetch | Fabaceae | |
| Astragalus newberryi var. castoreus | Newberry's milkvetch | Fabaceae | |
| Astragalus newberryi var. newberryi | Newberry's milkvetch | Fabaceae | |
| Astragalus nothoxys | sheep milkvetch | Fabaceae | |
| Astragalus nutriosensis | Apache milkvetch | Fabaceae | |
| Astragalus nuttallianus | smallflowered milkvetch | Fabaceae | |
| Astragalus nuttallianus var. austrinus | smallflowered milkvetch | Fabaceae | |
| Astragalus nuttallianus var. cedrosensis | turkeypeas | Fabaceae | |
| Astragalus nuttallianus var. imperfectus | turkeypeas | Fabaceae | |
| Astragalus nuttallianus var. micranthiformis | turkeypeas | Fabaceae | |
| Astragalus oophorus | egg milkvetch | Fabaceae | |
| Astragalus oophorus var. caulescens | egg milkvetch | Fabaceae | |
| Astragalus palmeri | Palmer's milkvetch | Fabaceae | |
| Astragalus pattersonii | Patterson's milkvetch | Fabaceae | |
| Astragalus pinonis | pinyon milkvetch | Fabaceae | |
| Astragalus pinonis var. atwoodii | Duane's milkvetch | Fabaceae | |
| Astragalus praelongus | stinking milkvetch | Fabaceae | |
| Astragalus praelongus var. lonchopus | stinking milkvetch | Fabaceae | |
| Astragalus praelongus var. praelongus | stinking milkvetch | Fabaceae | |
| Astragalus preussii | Preuss' milkvetch | Fabaceae | |
| Astragalus preussii var. laxiflorus | Preuss' milkvetch | Fabaceae | |
| Astragalus preussii var. preussii | Preuss' milkvetch | Fabaceae | |
| Astragalus recurvus | recurved milkvetch | Fabaceae | |
| Astragalus rusbyi | Rusby's milkvetch | Fabaceae | |
| Astragalus sabulonum | gravel milkvetch | Fabaceae | |
| Astragalus scopulorum | Rocky Mountain milkvetch | Fabaceae | |
| Astragalus sesquiflorus | sandstone milkvetch | Fabaceae | |
| Astragalus sophoroides | painted desert milkvetch | Fabaceae | |
| Astragalus straturensis | Pine Valley milkvetch | Fabaceae | |
| Astragalus striatiflorus | escarpment milkvetch | Fabaceae | |
| Astragalus subcinereus | Silver's milkvetch | Fabaceae | |
| Astragalus tephrodes | ashen milkvetch | Fabaceae | |
| Astragalus tephrodes var. brachylobus | ashen milkvetch | Fabaceae | |
| Astragalus tephrodes var. chloridae | ashen milkvetch | Fabaceae | |
| Astragalus tephrodes var. tephrodes | ashen milkvetch | Fabaceae | |
| Astragalus tetrapterus | fourwing milkvetch | Fabaceae | |
| Astragalus thurberi | Thurber's milkvetch | Fabaceae | |
| Astragalus titanophilus | limestone milkvetch | Fabaceae | |
| Astragalus toanus | Toano milkvetch | Fabaceae | |
| Astragalus toanus var. scidulus | Toano milkvetch | Fabaceae | |
| Astragalus troglodytus | creeping milkvetch | Fabaceae | |
| Astragalus vaccarum | Cow Spring milkvetch | Fabaceae | |
| Astragalus wingatanus | Fort Wingate milkvetch | Fabaceae | |
| Astragalus xiphoides | gladiator milkvetch | Fabaceae | |
| Astragalus zionis | Zion milkvetch | Fabaceae | |
| Astragalus zionis var. zionis | Zion milkvetch | Fabaceae | |
| Astrolepis | cloakfern | Pteridaceae | |
| Astrolepis cochisensis | Cochise scaly cloakfern | Pteridaceae | |
| Astrolepis cochisensis ssp. arizonica | Arizona scaly cloakfern | Pteridaceae | |
| Astrolepis cochisensis ssp. cochisensis | Cochise scaly cloakfern | Pteridaceae | |
| Astrolepis integerrima | hybrid cloakfern | Pteridaceae | |
| Astrolepis sinuata | wavy scaly cloakfern | Pteridaceae | |
| Astrolepis sinuata ssp. sinuata | wavy scaly cloakfern | Pteridaceae | |
| Astrolepis windhamii | Windham's scaly cloakfern | Pteridaceae | |
| Atamisquea | atamisquea | Capparaceae | |
| Atamisquea emarginata | vomitbush | Capparaceae | |
| Athyrium | ladyfern | Dryopteridaceae | |
| Athyrium filix-femina | common ladyfern | Dryopteridaceae | |
| Athyrium filix-femina ssp. cyclosorum | subarctic ladyfern | Dryopteridaceae | |
| Athysanus | sandweed | Brassicaceae | |
| Athysanus pusillus | common sandweed | Brassicaceae | |
| Atrichoseris | atrichoseris | Asteraceae | |
| Atrichoseris platyphylla | parachute plant | Asteraceae | |
| Atriplex | saltbush | Chenopodiaceae | |
| Atriplex acanthocarpa | tubercled saltbush | Chenopodiaceae | |
| Atriplex acanthocarpa ssp. acanthocarpa | tubercled saltbush | Chenopodiaceae | |
| Atriplex argentea | silverscale saltbush | Chenopodiaceae | |
| Atriplex argentea ssp. argentea | silverscale saltbush | Chenopodiaceae | |
| Atriplex argentea ssp. argentea var. argentea | silverscale saltbush | Chenopodiaceae | |
| Atriplex argentea ssp. argentea var. caput-medusae | stalked saltbush | Chenopodiaceae | |
| Atriplex argentea ssp. expansa | silverscale saltbush | Chenopodiaceae | |
| Atriplex asterocarpa | Chinle saltbush | Chenopodiaceae | |
| Atriplex canescens | fourwing saltbush | Chenopodiaceae | |
| Atriplex canescens var. angustifolia | fourwing saltbush | Chenopodiaceae | |
| Atriplex canescens var. canescens | fourwing saltbush | Chenopodiaceae | |
| Atriplex canescens var. linearis | thinleaf fourwing saltbush | Chenopodiaceae | |
| Atriplex confertifolia | shadscale saltbush | Chenopodiaceae | |
| Atriplex cuneata | valley saltbush | Chenopodiaceae | |
| Atriplex cuneata ssp. cuneata | valley saltbush | Chenopodiaceae | |
| Atriplex elegans | wheelscale saltbush | Chenopodiaceae | |
| Atriplex elegans var. elegans | wheelscale saltbush | Chenopodiaceae | |
| Atriplex elegans var. fasciculata | wheelscale saltbush | Chenopodiaceae | |
| Atriplex elegans var. thornberi | wheelscale saltbush | Chenopodiaceae | |
| Atriplex garrettii | Garrett's saltbush | Chenopodiaceae | |
| Atriplex griffithsii | Griffiths' saltbush | Chenopodiaceae | |
| Atriplex hymenelytra | desertholly | Chenopodiaceae | |
| Atriplex lentiformis | big saltbush | Chenopodiaceae | |
| Atriplex lentiformis ssp. lentiformis | big saltbush | Chenopodiaceae | |
| Atriplex navajoensis | Navajo saltbush | Chenopodiaceae | |
| Atriplex obovata | mound saltbush | Chenopodiaceae | |
| Atriplex pacifica | Davidson's saltbush | Chenopodiaceae | |
| Atriplex phyllostegia | leafcover saltweed | Chenopodiaceae | |
| Atriplex polycarpa | cattle saltbush | Chenopodiaceae | |
| Atriplex powellii | Powell's saltweed | Chenopodiaceae | |
| Atriplex prostrata | triangle orache | Chenopodiaceae | |
| Atriplex rosea | tumbling saltweed | Chenopodiaceae | |
| Atriplex saccaria | sack saltbush | Chenopodiaceae | |
| Atriplex semibaccata | Australian saltbush | Chenopodiaceae | |
| Atriplex serenana | bractscale | Chenopodiaceae | |
| Atriplex serenana var. serenana | bractscale | Chenopodiaceae | |
| Atriplex subspicata | saline saltbush | Chenopodiaceae | |
| Atriplex torreyi | Torrey's saltbush | Chenopodiaceae | |
| Atriplex wrightii | Wright's saltbush | Chenopodiaceae | |
| Avena | oat | Poaceae | |
| Avena barbata | slender oat | Poaceae | |
| Avena fatua | wild oat | Poaceae | |
| Avena sativa | common oat | Poaceae | |
| Ayenia | ayenia | Sterculiaceae | |
| Ayenia ardua | wingstem ayenia | Sterculiaceae | |
| Ayenia compacta | California ayenia | Sterculiaceae | |
| Ayenia filiformis | Trans-Pecos ayenia | Sterculiaceae | |
| Ayenia glabra | smooth ayenia | Sterculiaceae | |
| Ayenia insulicola | dwarf ayenia | Sterculiaceae | |
| Ayenia microphylla | dense ayenia | Sterculiaceae | |
| Azolla | mosquitofern | Azollaceae | |
| Azolla filiculoides | Pacific mosquitofern | Azollaceae | |
| Azolla mexicana | Mexican mosquitofern | Azollaceae | |
| B | |||
| Baccharis | baccharis | Asteraceae | |
| Baccharis bigelovii | Bigelow's false willow | Asteraceae | |
| Baccharis brachyphylla | shortleaf baccharis | Asteraceae | |
| Baccharis emoryi | Emory's baccharis | Asteraceae | |
| Baccharis neglecta | Rooseveltweed | Asteraceae | |
| Baccharis pteronioides | yerba de pasmo | Asteraceae | |
| Baccharis salicifolia | mule-fat | Asteraceae | |
| Baccharis sarothroides | desertbroom | Asteraceae | |
| Baccharis sergiloides | desert baccharis | Asteraceae | |
| Baccharis thesioides | Arizona baccharis | Asteraceae | |
| Baccharis wrightii | Wright's baccharis | Asteraceae | |
| Bacopa | waterhyssop | Scrophulariaceae | |
| Bacopa monnieri | herb of grace | Scrophulariaceae | |
| Bacopa rotundifolia | disk waterhyssop | Scrophulariaceae | |
| Bahia | bahia | Asteraceae | |
| Bahia absinthifolia | hairyseed bahia | Asteraceae | |
| Bahia absinthifolia var. absinthifolia | hairyseed bahia | Asteraceae | |
| Bahia absinthifolia var. dealbata | Dealbata's bahia | Asteraceae | |
| Bahia biternata | slimlobe bahia | Asteraceae | |
| Bahia dissecta | ragleaf bahia | Asteraceae | |
| Baileya | desert marigold | Asteraceae | |
| Baileya multiradiata | desert marigold | Asteraceae | |
| Baileya pauciradiata | laxflower | Asteraceae | |
| Baileya pleniradiata | woolly desert marigold | Asteraceae | |
| Balsamorhiza | balsamroot | Asteraceae | |
| Balsamorhiza hookeri | Hooker's balsamroot | Asteraceae | |
| Balsamorhiza hookeri var. hispidula | hairy balsamroot | Asteraceae | |
| Balsamorhiza sagittata | arrowleaf balsamroot | Asteraceae | |
| Barbarea | yellowrocket | Brassicaceae | |
| Barbarea orthoceras | American yellowrocket | Brassicaceae | |
| Barkleyanthus | willow ragwort | Asteraceae | |
| Barkleyanthus salicifolius | willow ragwort | Asteraceae | |
| Bassia | smotherweed | Chenopodiaceae | |
| Bassia americana | green molly | Chenopodiaceae | |
| Bassia hyssopifolia | fivehorn smotherweed | Chenopodiaceae | |
| Bassia prostrata | forage kochia | Chenopodiaceae | |
| Bassia scoparia | burningbush | Chenopodiaceae | |
| Bebbia | sweetbush | Asteraceae | |
| Bebbia juncea | sweetbush | Asteraceae | |
| Bebbia juncea var. aspera | sweetbush | Asteraceae | |
| Beckmannia | sloughgrass | Poaceae | |
| Beckmannia syzigachne | American sloughgrass | Poaceae | |
| Berberis | barberry | Berberidaceae | |
| Berberis harrisoniana | Harrison's barberry | Berberidaceae | |
| Berberis wilcoxii | Wilcox's barberry | Berberidaceae | |
| Berlandiera | greeneyes | Asteraceae | |
| Berlandiera lyrata | lyreleaf greeneyes | Asteraceae | |
| Bernardia | myrtlecroton | Euphorbiaceae | |
| Bernardia myricifolia | mouse's eye | Euphorbiaceae | |
| Berula | waterparsnip | Apiaceae | |
| Berula erecta | cutleaf waterparsnip | Apiaceae | |
| Besseya | kittentail | Scrophulariaceae | |
| Besseya arizonica | Arizona coraldrops | Scrophulariaceae | |
| Besseya plantaginea | White River coraldrops | Scrophulariaceae | |
| Betula | birch | Betulaceae | |
| Betula occidentalis | water birch | Betulaceae | |
| Bidens | beggarticks | Asteraceae | |
| Bidens aurea | Arizona beggarticks | Asteraceae | |
| Bidens bigelovii | Bigelow's beggarticks | Asteraceae | |
| Bidens bigelovii var. angustiloba | Asteraceae | ||
| Bidens bigelovii var. bigelovii | Bigelow's beggarticks | Asteraceae | |
| Bidens bipinnata | Spanish needles | Asteraceae | |
| Bidens cernua | nodding beggartick | Asteraceae | |
| Bidens ferulifolia | Apache beggarticks | Asteraceae | |
| Bidens frondosa | devil's beggartick | Asteraceae | |
| Bidens heterosperma | Rocky Mountain beggarticks | Asteraceae | |
| Bidens laevis | smooth beggartick | Asteraceae | |
| Bidens lemmonii | Lemmon's beggarticks | Asteraceae | |
| Bidens leptocephala | fewflower beggarticks | Asteraceae | |
| Bidens pilosa | hairy beggarticks | Asteraceae | |
| Bidens tenuisecta | slimlobe beggarticks | Asteraceae | |
| Blepharoneuron | dropseed | Poaceae | |
| Blepharoneuron tricholepis | pine dropseed | Poaceae | |
| Boehmeria | false nettle | Urticaceae | |
| Boehmeria cylindrica | smallspike false nettle | Urticaceae | |
| Boerhavia | spiderling | Nyctaginaceae | |
| Boerhavia coccinea | scarlet spiderling | Nyctaginaceae | |
| Boerhavia coulteri | Coulter's spiderling | Nyctaginaceae | |
| Boerhavia erecta | erect spiderling | Nyctaginaceae | |
| Boerhavia gracillima | slimstalk spiderling | Nyctaginaceae | |
| Boerhavia intermedia | fivewing spiderling | Nyctaginaceae | |
| Boerhavia megaptera | Tucson Mountain spiderling | Nyctaginaceae | |
| Boerhavia pterocarpa | Apache Pass spiderling | Nyctaginaceae | |
| Boerhavia purpurascens | purple spiderling | Nyctaginaceae | |
| Boerhavia scandens | climbing wartclub | Nyctaginaceae | |
| Boerhavia spicata | creeping spiderling | Nyctaginaceae | |
| Boerhavia triquetra | slender spiderling | Nyctaginaceae | |
| Boerhavia wrightii | largebract spiderling | Nyctaginaceae | |
| Bommeria | bommeria fern | Pteridaceae | |
| Bommeria hispida | copper fern | Pteridaceae | |
| Bothriochloa | beardgrass | Poaceae | |
| Bothriochloa barbinodis | cane bluestem | Poaceae | |
| Bothriochloa ischaemum | yellow bluestem | Poaceae | |
| Bothriochloa ischaemum var. songarica | yellow bluestem | Poaceae | |
| Bothriochloa laguroides | silver beardgrass | Poaceae | |
| Bothriochloa laguroides ssp. torreyana | silver beardgrass | Poaceae | |
| Bothriochloa springfieldii | Springfield's beardgrass | Poaceae | |
| Bothriochloa wrightii | Wright's beardgrass | Poaceae | |
| Botrychium | grapefern | Ophioglossaceae | |
| Botrychium crenulatum | scalloped moonwort | Ophioglossaceae | |
| Botrychium echo | reflected grapefern | Ophioglossaceae | |
| Botrychium hesperium | western moonwort | Ophioglossaceae | |
| Botrychium lanceolatum | lanceleaf grapefern | Ophioglossaceae | |
| Botrychium lanceolatum var. lanceolatum | lanceleaf grapefern | Ophioglossaceae | |
| Botrychium lunaria | common moonwort | Ophioglossaceae | |
| Botrychium minganense | Mingan moonwort | Ophioglossaceae | |
| Botrychium multifidum | leathery grapefern | Ophioglossaceae | |
| Botrychium pinnatum | northern moonwort | Ophioglossaceae | |
| Botrychium virginianum | rattlesnake fern | Ophioglossaceae | |
| Bouchea | bouchea | Verbenaceae | |
| Bouchea prismatica | prism bouchea | Verbenaceae | |
| Bouteloua | grama | Poaceae | |
| Bouteloua aristidoides | needle grama | Poaceae | |
| Bouteloua aristidoides var. aristidoides | needle grama | Poaceae | |
| Bouteloua aristidoides var. arizonica | Arizona needle grama | Poaceae | |
| Bouteloua barbata | sixweeks grama | Poaceae | |
| Bouteloua chondrosioides | sprucetop grama | Poaceae | |
| Bouteloua curtipendula | sideoats grama | Poaceae | |
| Bouteloua curtipendula var. caespitosa | sideoats grama | Poaceae | |
| Bouteloua curtipendula var. curtipendula | sideoats grama | Poaceae | |
| Bouteloua dactyloides | buffalograss | Poaceae | |
| Bouteloua diversispicula | zacale | Poaceae | |
| Bouteloua eludens | Santa Rita Mountain grama | Poaceae | |
| Bouteloua eriopoda | black grama | Poaceae | |
| Bouteloua gracilis | blue grama | Poaceae | |
| Bouteloua hirsuta | hairy grama | Poaceae | |
| Bouteloua hirsuta var. hirsuta | hairy grama | Poaceae | |
| Bouteloua parryi | Parry's grama | Poaceae | |
| Bouteloua radicosa | purple grama | Poaceae | |
| Bouteloua repens | slender grama | Poaceae | |
| Bouteloua rothrockii | Rothrock's grama | Poaceae | |
| Bouteloua simplex | matted grama | Poaceae | |
| Bouteloua trifida | red grama | Poaceae | |
| Bouteloua trifida var. trifida | red grama | Poaceae | |
| Bouvardia | bouvardia | Rubiaceae | |
| Bouvardia ternifolia | firecrackerbush | Rubiaceae | |
| Bowlesia | bowlesia | Apiaceae | |
| Bowlesia incana | hoary bowlesia | Apiaceae | |
| Brachystigma | desert foxglove | Scrophulariaceae | |
| Brachystigma wrightii | Arizona desert foxglove | Scrophulariaceae | |
| Brandegea | starvine | Cucurbitaceae | |
| Brandegea bigelovii | desert starvine | Cucurbitaceae | |
| Brassica | mustard | Brassicaceae | |
| Brassica juncea | India mustard | Brassicaceae | |
| Brassica nigra | black mustard | Brassicaceae | |
| Brassica rapa | field mustard | Brassicaceae | |
| Brassica rapa var. rapa | field mustard | Brassicaceae | |
| Brassica tournefortii | Asian mustard | Brassicaceae | |
| Brickellia | brickellbush | Asteraceae | |
| Brickellia amplexicaulis | earleaf brickellbush | Asteraceae | |
| Brickellia amplexicaulis var. amplexicaulis | earleaf brickellbush | Asteraceae | |
| Brickellia amplexicaulis var. lanceolata | earleaf brickellbush | Asteraceae | |
| Brickellia atractyloides | spearleaf brickellbush | Asteraceae | |
| Brickellia baccharidea | resinleaf brickellbush | Asteraceae | |
| Brickellia betonicifolia | betonyleaf brickellbush | Asteraceae | |
| Brickellia brachyphylla | plumed brickellbush | Asteraceae | |
| Brickellia californica | California brickellbush | Asteraceae | |
| Brickellia californica var. californica | California brickellbush | Asteraceae | |
| Brickellia coulteri | Coulter's brickellbush | Asteraceae | |
| Brickellia desertorum | desert brickellbush | Asteraceae | |
| Brickellia eupatorioides | false boneset | Asteraceae | |
| Brickellia eupatorioides var. chlorolepis | false boneset | Asteraceae | |
| Brickellia floribunda | Chihuahuan brickellbush | Asteraceae | |
| Brickellia frutescens | shrubby brickellbush | Asteraceae | |
| Brickellia grandiflora | tasselflower brickellbush | Asteraceae | |
| Brickellia incana | woolly brickellbush | Asteraceae | |
| Brickellia lemmonii | Lemmon's brickellbush | Asteraceae | |
| Brickellia lemmonii var. lemmonii | Lemmon's brickellbush | Asteraceae | |
| Brickellia longifolia | longleaf brickellbush | Asteraceae | |
| Brickellia longifolia var. longifolia | longleaf brickellbush | Asteraceae | |
| Brickellia microphylla | littleleaf brickellbush | Asteraceae | |
| Brickellia microphylla var. scabra | rough brickellbush | Asteraceae | |
| Brickellia microphylla var. watsonii | Watson's brickellbush | Asteraceae | |
| Brickellia oblongifolia | Mojave brickellbush | Asteraceae | |
| Brickellia oblongifolia var. linifolia | narrowleaf brickellbush | Asteraceae | |
| Brickellia parvula | Mt. Davis brickellbush | Asteraceae | |
| Brickellia pringlei | Pringle's brickellbush | Asteraceae | |
| Brickellia rusbyi | stinking brickellbush | Asteraceae | |
| Brickellia simplex | Sonoran brickellbush | Asteraceae | |
| Brickellia venosa | veiny brickellbush | Asteraceae | |
| Brickelliastrum | brickellbush | Asteraceae | |
| Brickelliastrum fendleri | Fendler's brickellbush | Asteraceae | |
| Bromus | brome | Poaceae | |
| Bromus arenarius | Australian brome | Poaceae | |
| Bromus arizonicus | Arizona brome | Poaceae | |
| Bromus arvensis | field brome | Poaceae | |
| Bromus berteroanus | Chilean chess | Poaceae | |
| Bromus catharticus | rescuegrass | Poaceae | |
| Bromus ciliatus | fringed brome | Poaceae | |
| Bromus ciliatus var. ciliatus | fringed brome | Poaceae | |
| Bromus ciliatus var. richardsonii | fringed brome | Poaceae | |
| Bromus diandrus | ripgut brome | Poaceae | |
| Bromus diandrus ssp. rigidus | ripgut brome | Poaceae | |
| Bromus frondosus | weeping brome | Poaceae | |
| Bromus hordeaceus | soft brome | Poaceae | |
| Bromus hordeaceus ssp. hordeaceus | soft brome | Poaceae | |
| Bromus inermis | smooth brome | Poaceae | |
| Bromus inermis ssp. inermis | smooth brome | Poaceae | |
| Bromus inermis ssp. inermis var. inermis | smooth brome | Poaceae | |
| Bromus lanatipes | woolly brome | Poaceae | |
| Bromus madritensis | compact brome | Poaceae | |
| Bromus marginatus | mountain brome | Poaceae | |
| Bromus mucroglumis | sharpglume brome | Poaceae | |
| Bromus orcuttianus | Orcutt's brome | Poaceae | |
| Bromus polyanthus | Great Basin brome | Poaceae | |
| Bromus polyanthus var. paniculatus | Great Basin brome | Poaceae | |
| Bromus polyanthus var. polyanthus | Great Basin brome | Poaceae | |
| Bromus porteri | Porter brome | Poaceae | |
| Bromus racemosus | bald brome | Poaceae | |
| Bromus rubens | red brome | Poaceae | |
| Bromus secalinus | rye brome | Poaceae | |
| Bromus secalinus var. secalinus | rye brome | Poaceae | |
| Bromus sterilis | poverty brome | Poaceae | |
| Bromus tectorum | cheatgrass | Poaceae | |
| Browallia | browallia | Solanaceae | |
| Browallia eludens | bush-violet | Solanaceae | |
| Buchnera | bluehearts | Scrophulariaceae | |
| Buchnera obliqua | Arizona bluehearts | Scrophulariaceae | |
| Buddleja | butterflybush | Buddlejaceae | |
| Buddleja scordioides | escobilla butterflybush | Buddlejaceae | |
| Buddleja sessiliflora | Rio Grande butterflybush | Buddlejaceae | |
| Buddleja utahensis | Utah butterflybush | Buddlejaceae | |
| Bulbostylis | hairsedge | Cyperaceae | |
| Bulbostylis capillaris | densetuft hairsedge | Cyperaceae | |
| Bulbostylis capillaris ssp. capillaris | densetuft hairsedge | Cyperaceae | |
| Bulbostylis funckii | Funck's hairsedge | Cyperaceae | |
| Bulbostylis juncoides | rush hairsedge | Cyperaceae | |
| Bupleurum | bupleurum | Apiaceae | |
| Bupleurum lancifolium | lanceleaf thorow wax | Apiaceae | |
| Bupleurum rotundifolium | hare's ear | Apiaceae | |
| Bursera | bursera | Burseraceae | |
| Bursera fagaroides | fragrant bursera | Burseraceae | |
| Bursera fagaroides var. elongata | fragrant bursera | Burseraceae | |
| Bursera microphylla | elephant tree | Burseraceae | |
| C | |||
| Caesalpinia | nicker | Fabaceae | |
| Caesalpinia gilliesii | bird-of-paradise shrub | Fabaceae | |
| Caesalpinia mexicana | Mexican holdback | Fabaceae | |
| Caesalpinia pulcherrima | pride-of-Barbados | Fabaceae | |
| Calamagrostis | reedgrass | Poaceae | |
| Calamagrostis canadensis | bluejoint | Poaceae | |
| Calamagrostis canadensis var. canadensis | bluejoint | Poaceae | |
| Calamagrostis scopulorum | ditch reedgrass | Poaceae | |
| Calamagrostis stricta | slimstem reedgrass | Poaceae | |
| Calamagrostis stricta ssp. inexpansa | northern reedgrass | Poaceae | |
| Calamagrostis stricta ssp. stricta | slimstem reedgrass | Poaceae | |
| Calamagrostis stricta ssp. stricta var. stricta | slimstem reedgrass | Poaceae | |
| Calamovilfa | sandreed | Poaceae | |
| Calamovilfa gigantea | giant sandreed | Poaceae | |
| Calandrinia | redmaids | Portulacaceae | |
| Calandrinia ciliata | fringed redmaids | Portulacaceae | |
| Calibrachoa | calibrachoa | Solanaceae | |
| Calibrachoa parviflora | seaside petunia | Solanaceae | |
| Callaeum | callaeum | Malpighiaceae | |
| Callaeum macropterum | hillyhock | Malpighiaceae | |
| Calliandra | stickpea | Fabaceae | |
| Calliandra eriophylla | fairyduster | Fabaceae | |
| Calliandra humilis | dwarf stickpea | Fabaceae | |
| Calliandra humilis var. humilis | dwarf stickpea | Fabaceae | |
| Calliandra humilis var. reticulata | dwarf stickpea | Fabaceae | |
| Callirhoe | poppymallow | Malvaceae | |
| Callirhoe involucrata | purple poppymallow | Malvaceae | |
| Callirhoe involucrata var. involucrata | purple poppymallow | Malvaceae | |
| Callitriche | water-starwort | Callitrichaceae | |
| Callitriche hermaphroditica | northern water-starwort | Callitrichaceae | |
| Callitriche heterophylla | twoheaded water-starwort | Callitrichaceae | |
| Callitriche heterophylla ssp. heterophylla | twoheaded water-starwort | Callitrichaceae | |
| Callitriche palustris | vernal water-starwort | Callitrichaceae | |
| Calochortus | mariposa lily | Liliaceae | |
| Calochortus ambiguus | doubting mariposa lily | Liliaceae | |
| Calochortus aureus | golden mariposa lily | Liliaceae | |
| Calochortus flexuosus | winding mariposa lily | Liliaceae | |
| Calochortus gunnisonii | Gunnison's mariposa lily | Liliaceae | |
| Calochortus gunnisonii var. gunnisonii | Gunnison's mariposa lily | Liliaceae | |
| Calochortus kennedyi | desert mariposa lily | Liliaceae | |
| Calochortus kennedyi var. kennedyi | desert mariposa lily | Liliaceae | |
| Calochortus nuttallii | sego lily | Liliaceae | |
| Caltha | marsh marigold | Ranunculaceae | |
| Caltha leptosepala | white marsh marigold | Ranunculaceae | |
| Caltha leptosepala ssp. leptosepala | white marsh marigold | Ranunculaceae | |
| Caltha leptosepala ssp. leptosepala var. leptosepala | white marsh marigold | Ranunculaceae | |
| Calycoseris | tackstem | Asteraceae | |
| Calycoseris parryi | yellow tackstem | Asteraceae | |
| Calycoseris wrightii | white tackstem | Asteraceae | |
| Calylophus | sundrops | Onagraceae | |
| Calylophus hartwegii | Hartweg's sundrops | Onagraceae | |
| Calylophus hartwegii ssp. fendleri | Hartweg's sundrops | Onagraceae | |
| Calylophus hartwegii ssp. pubescens | Hartweg's sundrops | Onagraceae | |
| Calylophus lavandulifolius | lavenderleaf sundrops | Onagraceae | |
| Calylophus serrulatus | yellow sundrops | Onagraceae | |
| Calylophus toumeyi | Toumey's sundrops | Onagraceae | |
| Calypso | fairy slipper | Orchidaceae | |
| Calypso bulbosa | fairy slipper | Orchidaceae | |
| Calypso bulbosa var. americana | fairy slipper | Orchidaceae | |
| Calyptocarpus | calyptocarpus | Asteraceae | |
| Calyptocarpus vialis | straggler daisy | Asteraceae | |
| Calystegia | false bindweed | Convolvulaceae | |
| Calystegia longipes | Paiute false bindweed | Convolvulaceae | |
| Calystegia macounii | Macoun's false bindweed | Convolvulaceae | |
| Calystegia sepium | hedge false bindweed | Convolvulaceae | |
| Calystegia sepium ssp. angulata | hedge false bindweed | Convolvulaceae | |
| Camelina | false flax | Brassicaceae | |
| Camelina microcarpa | littlepod false flax | Brassicaceae | |
| Camelina sativa | gold-of-pleasure | Brassicaceae | |
| Camelina sativa ssp. sativa | gold-of-pleasure | Brassicaceae | |
| Camissonia | suncup | Onagraceae | |
| Camissonia arenaria | Fortuna Range suncup | Onagraceae | |
| Camissonia boothii | Booth's evening primrose | Onagraceae | |
| Camissonia boothii ssp. alyssoides | alyssum evening primrose | Onagraceae | |
| Camissonia boothii ssp. boothii | Booth's suncup | Onagraceae | |
| Camissonia boothii ssp. condensata | shredding suncup | Onagraceae | |
| Camissonia boothii ssp. decorticans | shredding suncup | Onagraceae | |
| Camissonia brevipes | yellow cups | Onagraceae | |
| Camissonia brevipes ssp. arizonica | golden suncup | Onagraceae | |
| Camissonia brevipes ssp. brevipes | golden suncup | Onagraceae | |
| Camissonia brevipes ssp. pallidula | pallid suncup | Onagraceae | |
| Camissonia californica | California suncup | Onagraceae | |
| Camissonia cardiophylla | heartleaf suncup | Onagraceae | |
| Camissonia cardiophylla ssp. cardiophylla | heartleaf suncup | Onagraceae | |
| Camissonia chamaenerioides | longcapsule suncup | Onagraceae | |
| Camissonia claviformis | browneyes | Onagraceae | |
| Camissonia claviformis ssp. aurantiaca | browneyes | Onagraceae | |
| Camissonia claviformis ssp. claviformis | browneyes | Onagraceae | |
| Camissonia claviformis ssp. peeblesii | Peebles' browneyes | Onagraceae | |
| Camissonia claviformis ssp. peirsonii | Peirson's browneyes | Onagraceae | |
| Camissonia claviformis ssp. rubescens | browneyes | Onagraceae | |
| Camissonia claviformis ssp. yumae | Yuma browneyes | Onagraceae | |
| Camissonia confertiflora | Grand Canyon suncup | Onagraceae | |
| Camissonia confusa | San Bernardino suncup | Onagraceae | |
| Camissonia eastwoodiae | Grand Junction camissonia | Onagraceae | |
| Camissonia exilis | Cottonwood Springs suncup | Onagraceae | |
| Camissonia gouldii | Diamond Valley suncup | Onagraceae | |
| Camissonia multijuga | froststem suncup | Onagraceae | |
| Camissonia pallida | paleyellow suncup | Onagraceae | |
| Camissonia pallida ssp. pallida | paleyellow suncup | Onagraceae | |
| Camissonia palmeri | Palmer evening primrose | Onagraceae | |
| Camissonia parryi | redclay suncup | Onagraceae | |
| Camissonia parvula | Lewis River suncup | Onagraceae | |
| Camissonia pterosperma | wingfruit suncup | Onagraceae | |
| Camissonia refracta | narrowleaf suncup | Onagraceae | |
| Camissonia scapoidea | Paiute suncup | Onagraceae | |
| Camissonia scapoidea ssp. macrocarpa | Paiute suncup | Onagraceae | |
| Camissonia scapoidea ssp. scapoidea | Paiute suncup | Onagraceae | |
| Camissonia specuicola | Kaibab suncup | Onagraceae | |
| Camissonia specuicola ssp. hesperia | Kaibab suncup | Onagraceae | |
| Camissonia specuicola ssp. specuicola | Kaibab suncup | Onagraceae | |
| Camissonia walkeri | Walker's suncup | Onagraceae | |
| Camissonia walkeri ssp. walkeri | Walker's suncup | Onagraceae | |
| Campanula | bellflower | Campanulaceae | |
| Campanula parryi | Parry's bellflower | Campanulaceae | |
| Campanula parryi var. parryi | Parry's bellflower | Campanulaceae | |
| Campanula rotundifolia | bluebell bellflower | Campanulaceae | |
| Canavalia | jackbean | Fabaceae | |
| Canavalia ensiformis | wonderbean | Fabaceae | |
| Cannabis | hemp | Cannabaceae | |
| Cannabis sativa | marijuana | Cannabaceae | |
| Cannabis sativa ssp. sativa | marijuana | Cannabaceae | |
| Cannabis sativa ssp. sativa var. sativa | marijuana | Cannabaceae | |
| Canotia | canotia | Celastraceae | |
| Canotia holacantha | crucifixion thorn | Celastraceae | |
| Capsella | capsella | Brassicaceae | |
| Capsella bursa-pastoris | shepherd's purse | Brassicaceae | |
| Capsicum | pepper | Solanaceae | |
| Capsicum annuum | cayenne pepper | Solanaceae | |
| Capsicum annuum var. glabriusculum | cayenne pepper | Solanaceae | |
| Cardamine | bittercress | Brassicaceae | |
| Cardamine cordifolia | heartleaf bittercress | Brassicaceae | |
| Cardamine cordifolia var. cordifolia | heartleaf bittercress | Brassicaceae | |
| Cardamine hirsuta | hairy bittercress | Brassicaceae | |
| Cardamine parviflora | sand bittercress | Brassicaceae | |
| Cardamine parviflora var. arenicola | sand bittercress | Brassicaceae | |
| Cardaria | whitetop | Brassicaceae | |
| Cardaria draba | whitetop | Brassicaceae | |
| Cardaria pubescens | hairy whitetop | Brassicaceae | |
| Cardiospermum | balloonvine | Sapindaceae | |
| Cardiospermum corindum | faux persil | Sapindaceae | |
| Carduus | plumeless thistle | Asteraceae | |
| Carduus nutans | nodding plumeless thistle | Asteraceae | |
| Carex | sedge | Cyperaceae | |
| Carex agrostoides | grassleaf sedge | Cyperaceae | |
| Carex albonigra | blackandwhite sedge | Cyperaceae | |
| Carex alma | sturdy sedge | Cyperaceae | |
| Carex aquatilis | water sedge | Cyperaceae | |
| Carex aquatilis var. aquatilis | water sedge | Cyperaceae | |
| Carex atherodes | wheat sedge | Cyperaceae | |
| Carex athrostachya | slenderbeak sedge | Cyperaceae | |
| Carex aurea | golden sedge | Cyperaceae | |
| Carex bella | southwestern showy sedge | Cyperaceae | |
| Carex bolanderi | Bolander's sedge | Cyperaceae | |
| Carex brevior | shortbeak sedge | Cyperaceae | |
| Carex canescens | silvery sedge | Cyperaceae | |
| Carex canescens ssp. canescens | silvery sedge | Cyperaceae | |
| Carex chihuahuensis | Chihuahuan sedge | Cyperaceae | |
| Carex conoidea | openfield sedge | Cyperaceae | |
| Carex curatorum | Kaibab sedge | Cyperaceae | |
| Carex disperma | softleaf sedge | Cyperaceae | |
| Carex douglasii | Douglas' sedge | Cyperaceae | |
| Carex duriuscula | needleleaf sedge | Cyperaceae | |
| Carex ebenea | ebony sedge | Cyperaceae | |
| Carex elynoides | blackroot sedge | Cyperaceae | |
| Carex filifolia | threadleaf sedge | Cyperaceae | |
| Carex geophila | White Mountain sedge | Cyperaceae | |
| Carex hassei | salt sedge | Cyperaceae | |
| Carex haydeniana | cloud sedge | Cyperaceae | |
| Carex heteroneura | different-nerve sedge | Cyperaceae | |
| Carex heteroneura var. chalciolepis | Holm sedge | Cyperaceae | |
| Carex heteroneura var. epapillosa | different-nerve sedge | Cyperaceae | |
| Carex hystericina | bottlebrush sedge | Cyperaceae | |
| Carex interior | inland sedge | Cyperaceae | |
| Carex lativena | broadvein sedge | Cyperaceae | |
| Carex lenticularis | lakeshore sedge | Cyperaceae | |
| Carex lenticularis var. lipocarpa | Kellogg's sedge | Cyperaceae | |
| Carex leptopoda | taperfruit shortscale sedge | Cyperaceae | |
| Carex leucodonta | Huachuca Mountain sedge | Cyperaceae | |
| Carex mariposana | Mariposa sedge | Cyperaceae | |
| Carex meadii | Mead's sedge | Cyperaceae | |
| Carex microdonta | littletooth sedge | Cyperaceae | |
| Carex microptera | smallwing sedge | Cyperaceae | |
| Carex nebrascensis | Nebraska sedge | Cyperaceae | |
| Carex occidentalis | western sedge | Cyperaceae | |
| Carex oreocharis | grassyslope sedge | Cyperaceae | |
| Carex pellita | woolly sedge | Cyperaceae | |
| Carex petasata | Liddon sedge | Cyperaceae | |
| Carex planostachys | cedar sedge | Cyperaceae | |
| Carex praegracilis | clustered field sedge | Cyperaceae | |
| Carex rossii | Ross' sedge | Cyperaceae | |
| Carex scoparia | broom sedge | Cyperaceae | |
| Carex scoparia var. scoparia | broom sedge | Cyperaceae | |
| Carex scopulorum | mountain sedge | Cyperaceae | |
| Carex scopulorum var. bracteosa | mountain sedge | Cyperaceae | |
| Carex senta | swamp carex | Cyperaceae | |
| Carex serratodens | twotooth sedge | Cyperaceae | |
| Carex siccata | dryspike sedge | Cyperaceae | |
| Carex simulata | analogue sedge | Cyperaceae | |
| Carex specuicola | Navajo sedge | Cyperaceae | |
| Carex spissa | San Diego sedge | Cyperaceae | |
| Carex stipata | awlfruit sedge | Cyperaceae | |
| Carex stipata var. stipata | owlfruit sedge | Cyperaceae | |
| Carex subfusca | brown sedge | Cyperaceae | |
| Carex tahoensis | Tahoe sedge | Cyperaceae | |
| Carex thurberi | Thurber's sedge | Cyperaceae | |
| Carex ultra | Cochise sedge | Cyperaceae | |
| Carex vallicola | valley sedge | Cyperaceae | |
| Carex vallicola var. rusbyi | Rusby's sedge | Cyperaceae | |
| Carex vesicaria | blister sedge | Cyperaceae | |
| Carex vesicaria var. vesicaria | blister sedge | Cyperaceae | |
| Carex vulpinoidea | fox sedge | Cyperaceae | |
| Carex vulpinoidea var. vulpinoidea | fox sedge | Cyperaceae | |
| Carex wootonii | Wooton's sedge | Cyperaceae | |
| Carlowrightia | wrightwort | Acanthaceae | |
| Carlowrightia arizonica | Arizona wrightwort | Acanthaceae | |
| Carlowrightia linearifolia | heath wrightwort | Acanthaceae | |
| Carminatia | carminatia | Asteraceae | |
| Carminatia tenuiflora | plumeweed | Asteraceae | |
| Carnegiea | saguaro | Cactaceae | |
| Carnegiea gigantea | saguaro | Cactaceae | |
| Carphochaete | bristlehead | Asteraceae | |
| Carphochaete bigelovii | Bigelow's bristlehead | Asteraceae | |
| Carthamus | distaff thistle | Asteraceae | |
| Carthamus lanatus | woolly distaff thistle | Asteraceae | |
| Carthamus lanatus ssp. creticus | woolly distaff thistle | Asteraceae | |
| Carthamus tinctorius | safflower | Asteraceae | |
| Castalis | castalis | Asteraceae | |
| Castalis tragus | Cape marigold | Asteraceae | |
| Castela | castela | Simaroubaceae | |
| Castela emoryi | crucifixion thorn | Simaroubaceae | |
| Castilleja | Indian paintbrush | Scrophulariaceae | |
| Castilleja angustifolia | northwestern Indian paintbrush | Scrophulariaceae | |
| Castilleja angustifolia var. dubia | Scrophulariaceae | ||
| Castilleja attenuata | attenuate Indian paintbrush | Scrophulariaceae | |
| Castilleja austromontana | Rincon Mountain Indian paintbrush | Scrophulariaceae | |
| Castilleja exserta | exserted Indian paintbrush | Scrophulariaceae | |
| Castilleja exserta ssp. exserta | exserted Indian paintbrush | Scrophulariaceae | |
| Castilleja integra | wholeleaf Indian paintbrush | Scrophulariaceae | |
| Castilleja integra var. gloriosa | wholeleaf Indian paintbrush | Scrophulariaceae | |
| Castilleja integra var. integra | wholeleaf Indian paintbrush | Scrophulariaceae | |
| Castilleja kaibabensis | Kaibab Plateau Indian paintbrush | Scrophulariaceae | |
| Castilleja lanata | Sierra woolly Indian paintbrush | Scrophulariaceae | |
| Castilleja lanata ssp. lanata | Sierra woolly Indian paintbrush | Scrophulariaceae | |
| Castilleja linariifolia | Wyoming Indian paintbrush | Scrophulariaceae | |
| Castilleja lineata | marshmeadow Indian paintbrush | Scrophulariaceae | |
| Castilleja miniata | giant red Indian paintbrush | Scrophulariaceae | |
| Castilleja miniata ssp. miniata | giant red Indian paintbrush | Scrophulariaceae | |
| Castilleja minor | lesser Indian paintbrush | Scrophulariaceae | |
| Castilleja minor ssp. minor | lesser Indian paintbrush | Scrophulariaceae | |
| Castilleja minor ssp. spiralis | lesser Indian paintbrush | Scrophulariaceae | |
| Castilleja nervata | Trans-Pecos Indian paintbrush | Scrophulariaceae | |
| Castilleja patriotica | Huachuca Mountain Indian paintbrush | Scrophulariaceae | |
| Castilleja sessiliflora | downy paintedcup | Scrophulariaceae | |
| Castilleja sulphurea | sulphur Indian paintbrush | Scrophulariaceae | |
| Castilleja tenuiflora | Santa Catalina Indian paintbrush | Scrophulariaceae | |
| Catabrosa | whorlgrass | Poaceae | |
| Catabrosa aquatica | water whorlgrass | Poaceae | |
| Catabrosa aquatica var. aquatica | water whorlgrass | Poaceae | |
| Catalpa | catalpa | Bignoniaceae | |
| Catalpa bignonioides | southern catalpa | Bignoniaceae | |
| Cathestecum | false grama | Poaceae | |
| Cathestecum erectum | false grama | Poaceae | |
| Caulanthus | wild cabbage | Brassicaceae | |
| Caulanthus cooperi | Cooper's wild cabbage | Brassicaceae | |
| Ceanothus | ceanothus | Rhamnaceae | |
| Ceanothus fendleri | Fendler's ceanothus | Rhamnaceae | |
| Ceanothus greggii | desert ceanothus | Rhamnaceae | |
| Ceanothus greggii var. greggii | desert ceanothus | Rhamnaceae | |
| Ceanothus greggii var. perplexans | desert ceanothus | Rhamnaceae | |
| Ceanothus greggii var. vestitus | Mojave ceanothus | Rhamnaceae | |
| Ceanothus integerrimus | deerbrush | Rhamnaceae | |
| Ceanothus martinii | Martin's ceanothus | Rhamnaceae | |
| Celtis | hackberry | Ulmaceae | |
| Celtis ehrenbergiana | spiny hackberry | Ulmaceae | |
| Celtis laevigata | sugarberry | Ulmaceae | |
| Celtis laevigata var. brevipes | sugarberry | Ulmaceae | |
| Celtis laevigata var. reticulata | netleaf hackberry | Ulmaceae | |
| Cenchrus | sandbur | Poaceae | |
| Cenchrus echinatus | southern sandbur | Poaceae | |
| Cenchrus longispinus | mat sandbur | Poaceae | |
| Cenchrus spinifex | coastal sandbur | Poaceae | |
| Centaurea | knapweed | Asteraceae | |
| Centaurea americana | American star-thistle | Asteraceae | |
| Centaurea calcitrapa | red star-thistle | Asteraceae | |
| Centaurea cyanus | garden cornflower | Asteraceae | |
| Centaurea diffusa | diffuse knapweed | Asteraceae | |
| Centaurea melitensis | Maltese star-thistle | Asteraceae | |
| Centaurea rothrockii | Rothrock's knapweed | Asteraceae | |
| Centaurea solstitialis | yellow star-thistle | Asteraceae | |
| Centaurea stoebe | spotted knapweed | Asteraceae | |
| Centaurea stoebe ssp. micranthos | spotted knapweed | Asteraceae | |
| Centaurium | centaury | Gentianaceae | |
| Centaurium arizonicum | Arizona centaury | Gentianaceae | |
| Centaurium exaltatum | desert centaury | Gentianaceae | |
| Centaurium nudicaule | Santa Catalina Mountain centaury | Gentianaceae | |
| Centranthus | centranthus | Valerianaceae | |
| Centranthus ruber | red valerian | Valerianaceae | |
| Centromadia | Asteraceae | ||
| Centromadia pungens | common tarweed | Asteraceae | |
| Centromadia pungens ssp. pungens | common tarweed | Asteraceae | |
| Centrostegia | centrostegia | Polygonaceae | |
| Centrostegia thurberi | red triangles | Polygonaceae | |
| Cephalanthus | buttonbush | Rubiaceae | |
| Cephalanthus occidentalis | common buttonbush | Rubiaceae | |
| Cerastium | mouse-ear chickweed | Caryophyllaceae | |
| Cerastium arvense | field chickweed | Caryophyllaceae | |
| Cerastium arvense ssp. strictum | field chickweed | Caryophyllaceae | |
| Cerastium beeringianum | Bering chickweed | Caryophyllaceae | |
| Cerastium beeringianum ssp. earlei | Bering chickweed | Caryophyllaceae | |
| Cerastium brachypodum | shortstalk chickweed | Caryophyllaceae | |
| Cerastium fontanum | common mouse-ear chickweed | Caryophyllaceae | |
| Cerastium fontanum ssp. vulgare | big chickweed | Caryophyllaceae | |
| Cerastium gracile | slender chickweed | Caryophyllaceae | |
| Cerastium nutans | nodding chickweed | Caryophyllaceae | |
| Cerastium nutans var. nutans | nodding chickweed | Caryophyllaceae | |
| Cerastium nutans var. obtectum | nodding chickweed | Caryophyllaceae | |
| Cerastium sordidum | Chihuahuan chickweed | Caryophyllaceae | |
| Cerastium texanum | Texas chickweed | Caryophyllaceae | |
| Ceratocephala | curveseed butterwort | Ranunculaceae | |
| Ceratocephala testiculata | curveseed butterwort | Ranunculaceae | |
| Ceratonia | ceratonia | Fabaceae | |
| Ceratonia siliqua | St. John's bread | Fabaceae | |
| Ceratophyllum | hornwort | Ceratophyllaceae | |
| Ceratophyllum demersum | coon's tail | Ceratophyllaceae | |
| Cercis | redbud | Fabaceae | |
| Cercis orbiculata | California redbud | Fabaceae | |
| Cercocarpus | mountain mahogany | Rosaceae | |
| Cercocarpus intricatus | littleleaf mountain mahogany | Rosaceae | |
| Cercocarpus ledifolius | curl-leaf mountain mahogany | Rosaceae | |
| Cercocarpus ledifolius var. intercedens | curl-leaf mountain mahogany | Rosaceae | |
| Cercocarpus ledifolius var. ledifolius | curl-leaf mountain mahogany | Rosaceae | |
| Cercocarpus montanus | alderleaf mountain mahogany | Rosaceae | |
| Cercocarpus montanus var. glaber | birchleaf mountain mahogany | Rosaceae | |
| Cercocarpus montanus var. montanus | alderleaf mountain mahogany | Rosaceae | |
| Cercocarpus montanus var. paucidentatus | hairy mountain mahogany | Rosaceae | |
| Cevallia | stinging serpent | Loasaceae | |
| Cevallia sinuata | stinging serpent | Loasaceae | |
| Chaenactis | pincushion | Asteraceae | |
| Chaenactis carphoclinia | pebble pincushion | Asteraceae | |
| Chaenactis carphoclinia var. carphoclinia | pebble pincushion | Asteraceae | |
| Chaenactis douglasii | Douglas' dustymaiden | Asteraceae | |
| Chaenactis douglasii var. douglasii | Douglas' dustymaiden | Asteraceae | |
| Chaenactis fremontii | pincushion flower | Asteraceae | |
| Chaenactis macrantha | bighead dustymaiden | Asteraceae | |
| Chaenactis stevioides | Esteve's pincushion | Asteraceae | |
| Chaenactis xantiana | fleshcolor pincushion | Asteraceae | |
| Chaerophyllum | chervil | Apiaceae | |
| Chaerophyllum tainturieri | hairyfruit chervil | Apiaceae | |
| Chaerophyllum tainturieri var. tainturieri | hairyfruit chervil | Apiaceae | |
| Chaetopappa | leastdaisy | Asteraceae | |
| Chaetopappa ericoides | rose heath | Asteraceae | |
| Chamaebatiaria | desert sweet | Rosaceae | |
| Chamaebatiaria millefolium | desert sweet | Rosaceae | |
| Chamaechaenactis | chamaechaenactis | Asteraceae | |
| Chamaechaenactis scaposa | fullstem | Asteraceae | |
| Chamaechaenactis scaposa var. scaposa | fullstem | Asteraceae | |
| Chamaecrista | sensitive pea | Fabaceae | |
| Chamaecrista absus | tropical sensitive pea | Fabaceae | |
| Chamaecrista absus var. meonandra | tropical sensitive pea | Fabaceae | |
| Chamaecrista nictitans | sensitive partridge pea | Fabaceae | |
| Chamaecrista nictitans ssp. nictitans | sensitive partridge pea | Fabaceae | |
| Chamaecrista nictitans ssp. nictitans var. leptadenia | sensitive partridge pea | Fabaceae | |
| Chamaecrista serpens | slender sensitive pea | Fabaceae | |
| Chamaecrista serpens var. wrightii | Wright's sensitive pea | Fabaceae | |
| Chamaesaracha | five eyes | Solanaceae | |
| Chamaesaracha coronopus | greenleaf five eyes | Solanaceae | |
| Chamaesaracha sordida | hairy five eyes | Solanaceae | |
| Chamaesyce | sandmat | Euphorbiaceae | |
| Chamaesyce abramsiana | Abrams' sandmat | Euphorbiaceae | |
| Chamaesyce albomarginata | whitemargin sandmat | Euphorbiaceae | |
| Chamaesyce arizonica | Arizona sandmat | Euphorbiaceae | |
| Chamaesyce capitellata | head sandmat | Euphorbiaceae | |
| Chamaesyce chaetocalyx | bristlecup sandmat | Euphorbiaceae | |
| Chamaesyce chaetocalyx var. chaetocalyx | bristlecup sandmat | Euphorbiaceae | |
| Chamaesyce dioica | royal sandmat | Euphorbiaceae | |
| Chamaesyce fendleri | Fendler's sandmat | Euphorbiaceae | |
| Chamaesyce florida | Chiricahua Mountain sandmat | Euphorbiaceae | |
| Chamaesyce glyptosperma | ribseed sandmat | Euphorbiaceae | |
| Chamaesyce gracillima | Mexican sandmat | Euphorbiaceae | |
| Chamaesyce hirta | pillpod sandmat | Euphorbiaceae | |
| Chamaesyce hypericifolia | graceful sandmat | Euphorbiaceae | |
| Chamaesyce hyssopifolia | hyssopleaf sandmat | Euphorbiaceae | |
| Chamaesyce maculata | spotted sandmat | Euphorbiaceae | |
| Chamaesyce melanadenia | red-gland spurge | Euphorbiaceae | |
| Chamaesyce micromera | Sonoran sandmat | Euphorbiaceae | |
| Chamaesyce ocellata | Contura Creek sandmat | Euphorbiaceae | |
| Chamaesyce ocellata ssp. arenicola | Contura Creek sandmat | Euphorbiaceae | |
| Chamaesyce parryi | Parry's sandmat | Euphorbiaceae | |
| Chamaesyce pediculifera | Carrizo Mountain sandmat | Euphorbiaceae | |
| Chamaesyce platysperma | flatseed sandmat | Euphorbiaceae | |
| Chamaesyce polycarpa | smallseed sandmat | Euphorbiaceae | |
| Chamaesyce prostrata | prostrate sandmat | Euphorbiaceae | |
| Chamaesyce revoluta | threadstem sandmat | Euphorbiaceae | |
| Chamaesyce serpens | matted sandmat | Euphorbiaceae | |
| Chamaesyce serpyllifolia | thymeleaf sandmat | Euphorbiaceae | |
| Chamaesyce serpyllifolia ssp. serpyllifolia | thymeleaf sandmat | Euphorbiaceae | |
| Chamaesyce serrula | sawtooth sandmat | Euphorbiaceae | |
| Chamaesyce setiloba | Yuma sandmat | Euphorbiaceae | |
| Chamaesyce stictospora | slimseed sandmat | Euphorbiaceae | |
| Chamaesyce trachysperma | San Pedro River sandmat | Euphorbiaceae | |
| Chamaesyce vermiculata | wormseed sandmat | Euphorbiaceae | |
| Chamerion | fireweed | Onagraceae | |
| Chamerion angustifolium | fireweed | Onagraceae | |
| Chamerion angustifolium ssp. circumvagum | fireweed | Onagraceae | |
| Chasmanthium | woodoats | Poaceae | |
| Chasmanthium latifolium | Indian woodoats | Poaceae | |
| Cheilanthes | lipfern | Pteridaceae | |
| Cheilanthes alabamensis | Alabama lipfern | Pteridaceae | |
| Cheilanthes arizonica | Arizona lipfern | Pteridaceae | |
| Cheilanthes bonariensis | golden lipfern | Pteridaceae | |
| Cheilanthes covillei | Coville's lipfern | Pteridaceae | |
| Cheilanthes eatonii | Eaton's lipfern | Pteridaceae | |
| Cheilanthes feei | slender lipfern | Pteridaceae | |
| Cheilanthes fendleri | Fendler's lipfern | Pteridaceae | |
| Cheilanthes lendigera | nitbearing lipfern | Pteridaceae | |
| Cheilanthes lindheimeri | fairyswords | Pteridaceae | |
| Cheilanthes parishii | Pteridaceae | ||
| Cheilanthes parryi | Parry's lipfern | Pteridaceae | |
| Cheilanthes pringlei | Pringle's lipfern | Pteridaceae | |
| Cheilanthes tomentosa | woolly lipfern | Pteridaceae | |
| Cheilanthes villosa | villous lipfern | Pteridaceae | |
| Cheilanthes wootonii | beaded lipfern | Pteridaceae | |
| Cheilanthes wrightii | Wright's lipfern | Pteridaceae | |
| Cheilanthes yavapensis | graceful lipfern | Pteridaceae | |
| Chenopodium | goosefoot | Chenopodiaceae | |
| Chenopodium album | lambsquarters | Chenopodiaceae | |
| Chenopodium album var. album | lambsquarters | Chenopodiaceae | |
| Chenopodium ambrosioides | Mexican tea | Chenopodiaceae | |
| Chenopodium ambrosioides var. ambrosioides | Mexican tea | Chenopodiaceae | |
| Chenopodium atrovirens | pinyon goosefoot | Chenopodiaceae | |
| Chenopodium berlandieri | pitseed goosefoot | Chenopodiaceae | |
| Chenopodium berlandieri var. berlandieri | pitseed goosefoot | Chenopodiaceae | |
| Chenopodium berlandieri var. sinuatum | pitseed goosefoot | Chenopodiaceae | |
| Chenopodium berlandieri var. zschackii | Zschack's goosefoot | Chenopodiaceae | |
| Chenopodium botrys | Jerusalem oak goosefoot | Chenopodiaceae | |
| Chenopodium capitatum | blite goosefoot | Chenopodiaceae | |
| Chenopodium desiccatum | aridland goosefoot | Chenopodiaceae | |
| Chenopodium ficifolium | figleaf goosefoot | Chenopodiaceae | |
| Chenopodium fremontii | Fremont's goosefoot | Chenopodiaceae | |
| Chenopodium fremontii var. fremontii | Fremont's goosefoot | Chenopodiaceae | |
| Chenopodium graveolens | fetid goosefoot | Chenopodiaceae | |
| Chenopodium hians | hians goosefoot | Chenopodiaceae | |
| Chenopodium incanum | mealy goosefoot | Chenopodiaceae | |
| Chenopodium incanum var. elatum | mealy goosefoot | Chenopodiaceae | |
| Chenopodium incanum var. incanum | mealy goosefoot | Chenopodiaceae | |
| Chenopodium incanum var. occidentale | mealy goosefoot | Chenopodiaceae | |
| Chenopodium leptophyllum | narrowleaf goosefoot | Chenopodiaceae | |
| Chenopodium murale | nettleleaf goosefoot | Chenopodiaceae | |
| Chenopodium neomexicanum | New Mexico goosefoot | Chenopodiaceae | |
| Chenopodium neomexicanum var. neomexicanum | New Mexico goosefoot | Chenopodiaceae | |
| Chenopodium pratericola | desert goosefoot | Chenopodiaceae | |
| Chenopodium pumilio | clammy goosefoot | Chenopodiaceae | |
| Chenopodium rubrum | red goosefoot | Chenopodiaceae | |
| Chenopodium salinum | Rocky Mountain goosefoot | Chenopodiaceae | |
| Chenopodium watsonii | Watson's goosefoot | Chenopodiaceae | |
| Chilopsis | desert willow | Bignoniaceae | |
| Chilopsis linearis | desert willow | Bignoniaceae | |
| Chilopsis linearis ssp. arcuata | desert willow | Bignoniaceae | |
| Chimaphila | prince's pine | Pyrolaceae | |
| Chimaphila maculata | striped prince's pine | Pyrolaceae | |
| Chimaphila umbellata | pipsissewa | Pyrolaceae | |
| Chimaphila umbellata ssp. acuta | pipsissewa | Pyrolaceae | |
| Chloracantha | chloracantha | Asteraceae | |
| Chloracantha spinosa | spiny chloracantha | Asteraceae | |
| Chloris | windmill grass | Poaceae | |
| Chloris cucullata | hooded windmill grass | Poaceae | |
| Chloris gayana | Rhodes grass | Poaceae | |
| Chloris subdolichostachya | shortspike windmill grass | Poaceae | |
| Chloris verticillata | tumble windmill grass | Poaceae | |
| Chloris virgata | feather fingergrass | Poaceae | |
| Choisya | Mexican orange | Rutaceae | |
| Choisya dumosa | Mexican orange | Rutaceae | |
| Choisya dumosa var. arizonica | Arizonia orange | Rutaceae | |
| Choisya dumosa var. mollis | Mexican orange | Rutaceae | |
| Chorispora | chorispora | Brassicaceae | |
| Chorispora tenella | crossflower | Brassicaceae | |
| Chorizanthe | spineflower | Polygonaceae | |
| Chorizanthe brevicornu | brittle spineflower | Polygonaceae | |
| Chorizanthe brevicornu var. brevicornu | brittle spineflower | Polygonaceae | |
| Chorizanthe corrugata | wrinkled spineflower | Polygonaceae | |
| Chorizanthe rigida | devil's spineflower | Polygonaceae | |
| Chorizanthe watsonii | fivetooth spineflower | Polygonaceae | |
| Chromolaena | thoroughwort | Asteraceae | |
| Chromolaena bigelovii | Bigelow's thoroughwort | Asteraceae | |
| Chrysothamnus | rabbitbrush | Asteraceae | |
| Chrysothamnus baileyi | Bailey's rabbitbrush | Asteraceae | |
| Chrysothamnus depressus | longflower rabbitbrush | Asteraceae | |
| Chrysothamnus greenei | Greene's rabbitbrush | Asteraceae | |
| Chrysothamnus linifolius | spearleaf rabbitbrush | Asteraceae | |
| Chrysothamnus molestus | Arizona rabbitbrush | Asteraceae | |
| Chrysothamnus viscidiflorus | yellow rabbitbrush | Asteraceae | |
| Chrysothamnus viscidiflorus ssp. axillaris | yellow rabbitbrush | Asteraceae | |
| Chrysothamnus viscidiflorus ssp. lanceolatus | yellow rabbitbrush | Asteraceae | |
| Chrysothamnus viscidiflorus ssp. planifolius | yellow rabbitbrush | Asteraceae | |
| Chrysothamnus viscidiflorus ssp. puberulus | yellow rabbitbrush | Asteraceae | |
| Chrysothamnus viscidiflorus ssp. viscidiflorus | yellow rabbitbrush | Asteraceae | |
| Chrysothamnus viscidiflorus ssp. viscidiflorus var. stenophyllus | yellow rabbitbrush | Asteraceae | |
| Chrysothamnus viscidiflorus ssp. viscidiflorus var. viscidiflorus | yellow rabbitbrush | Asteraceae | |
| Cichorium | chicory | Asteraceae | |
| Cichorium intybus | chicory | Asteraceae | |
| Cicuta | water hemlock | Apiaceae | |
| Cicuta maculata | spotted water hemlock | Apiaceae | |
| Cicuta maculata var. angustifolia | spotted water hemlock | Apiaceae | |
| Cicuta maculata var. bolanderi | spotted water hemlock | Apiaceae | |
| Cicuta maculata var. maculata | spotted water hemlock | Apiaceae | |
| Cinna | woodreed | Poaceae | |
| Cinna latifolia | drooping woodreed | Poaceae | |
| Circaea | enchanter's nightshade | Onagraceae | |
| Circaea alpina | small enchanter's nightshade | Onagraceae | |
| Circaea alpina ssp. alpina | small enchanter's nightshade | Onagraceae | |
| Circaea alpina ssp. pacifica | small enchanter's nightshade | Onagraceae | |
| Cirsium | thistle | Asteraceae | |
| Cirsium arizonicum | Arizona thistle | Asteraceae | |
| Cirsium arvense | Canada thistle | Asteraceae | |
| Cirsium chellyense | queen thistle | Asteraceae | |
| Cirsium chuskaense | monarch thistle | Asteraceae | |
| Cirsium grahamii | Graham's thistle | Asteraceae | |
| Cirsium mohavense | Mojave thistle | Asteraceae | |
| Cirsium navajoense | Navajo thistle | Asteraceae | |
| Cirsium neomexicanum | New Mexico thistle | Asteraceae | |
| Cirsium ochrocentrum | yellowspine thistle | Asteraceae | |
| Cirsium ochrocentrum ssp. martinii | Asteraceae | ||
| Cirsium ochrocentrum ssp. ochrocentrum | yellowspine thistle | Asteraceae | |
| Cirsium parryi | Parry's thistle | Asteraceae | |
| Cirsium parryi ssp. mogollonicum | Mogollon thistle | Asteraceae | |
| Cirsium parryi ssp. parryi | Parry's thistle | Asteraceae | |
| Cirsium rothrockii | Rothrock's thistle | Asteraceae | |
| Cirsium rusbyi | Rusby's thistle | Asteraceae | |
| Cirsium rydbergii | Rydberg's thistle | Asteraceae | |
| Cirsium scariosum | meadow thistle | Asteraceae | |
| Cirsium undulatum | wavyleaf thistle | Asteraceae | |
| Cirsium undulatum var. undulatum | wavyleaf thistle | Asteraceae | |
| Cirsium virginense | virgin thistle | Asteraceae | |
| Cirsium vulgare | bull thistle | Asteraceae | |
| Cirsium wheeleri | Wheeler's thistle | Asteraceae | |
| Cirsium wrightii | Wright's thistle | Asteraceae | |
| Cissus | treebine | Vitaceae | |
| Cissus trifoliata | sorrelvine | Vitaceae | |
| Cistanthe | pussypaws | Portulacaceae | |
| Cistanthe ambigua | desert pussypaws | Portulacaceae | |
| Cistanthe monandra | common pussypaws | Portulacaceae | |
| Cistanthe parryi | Parry's pussypaws | Portulacaceae | |
| Cistanthe parryi var. arizonica | Arizona pussypaws | Portulacaceae | |
| Citrullus | watermelon | Cucurbitaceae | |
| Citrullus lanatus | watermelon | Cucurbitaceae | |
| Citrullus lanatus var. lanatus | watermelon | Cucurbitaceae | |
| Cladium | sawgrass | Cyperaceae | |
| Cladium californicum | California sawgrass | Cyperaceae | |
| Clarkia | clarkia | Onagraceae | |
| Clarkia epilobioides | canyon clarkia | Onagraceae | |
| Clarkia purpurea | winecup clarkia | Onagraceae | |
| Clarkia purpurea ssp. quadrivulnera | winecup clarkia | Onagraceae | |
| Clarkia rhomboidea | diamond clarkia | Onagraceae | |
| Claytonia | springbeauty | Portulacaceae | |
| Claytonia parviflora | streambank springbeauty | Portulacaceae | |
| Claytonia parviflora ssp. parviflora | streambank springbeauty | Portulacaceae | |
| Claytonia parviflora ssp. utahensis | streambank springbeauty | Portulacaceae | |
| Claytonia perfoliata | miner's lettuce | Portulacaceae | |
| Claytonia perfoliata ssp. intermontana | miner's lettuce | Portulacaceae | |
| Claytonia perfoliata ssp. mexicana | miner's lettuce | Portulacaceae | |
| Claytonia perfoliata ssp. perfoliata | miner's lettuce | Portulacaceae | |
| Claytonia rosea | western springbeauty | Portulacaceae | |
| Claytonia rubra | redstem springbeauty | Portulacaceae | |
| Claytonia rubra ssp. depressa | redstem springbeauty | Portulacaceae | |
| Claytonia rubra ssp. rubra | redstem springbeauty | Portulacaceae | |
| Clematis | leather flower | Ranunculaceae | |
| Clematis bigelovii | Bigelow's leather flower | Ranunculaceae | |
| Clematis columbiana | rock clematis | Ranunculaceae | |
| Clematis columbiana var. columbiana | rock clematis | Ranunculaceae | |
| Clematis drummondii | Drummond's clematis | Ranunculaceae | |
| Clematis hirsutissima | hairy clematis | Ranunculaceae | |
| Clematis hirsutissima var. arizonica | Arizona clematis | Ranunculaceae | |
| Clematis hirsutissima var. hirsutissima | hairy clematis | Ranunculaceae | |
| Clematis ligusticifolia | western white clematis | Ranunculaceae | |
| Clematis ligusticifolia var. ligusticifolia | western white clematis | Ranunculaceae | |
| Clematis palmeri | Palmer's leather flower | Ranunculaceae | |
| Cleome | spiderflower | Capparaceae | |
| Cleome isomeris | bladderpod spiderflower | Capparaceae | |
| Cleome lutea | yellow spiderflower | Capparaceae | |
| Cleome lutea var. jonesii | Jones spiderflower | Capparaceae | |
| Cleome lutea var. lutea | yellow spiderflower | Capparaceae | |
| Cleome multicaulis | slender spiderflower | Capparaceae | |
| Cleome serrulata | Rocky Mountain beeplant | Capparaceae | |
| Cleomella | stinkweed | Capparaceae | |
| Cleomella longipes | Chiricahua Mountain stinkweed | Capparaceae | |
| Cleomella obtusifolia | Mojave cleomella | Capparaceae | |
| Cleomella parviflora | slender cleomella | Capparaceae | |
| Cleomella plocasperma | twisted cleomella | Capparaceae | |
| Clinopodium | clinopodium | Lamiaceae | |
| Clinopodium vulgare | wild basil | Lamiaceae | |
| Clitoria | pigeonwings | Fabaceae | |
| Clitoria mariana | Atlantic pigeonwings | Fabaceae | |
| Cnicus | cnicus | Asteraceae | |
| Cnicus benedictus | blessed thistle | Asteraceae | |
| Cnidoscolus | cnidoscolus | Euphorbiaceae | |
| Cnidoscolus angustidens | mala mujer | Euphorbiaceae | |
| Cocculus | coralbead | Menispermaceae | |
| Cocculus diversifolius | snailseed | Menispermaceae | |
| Coleogyne | coleogyne | Rosaceae | |
| Coleogyne ramosissima | blackbrush | Rosaceae | |
| Collinsia | blue eyed Mary | Scrophulariaceae | |
| Collinsia parviflora | maiden blue eyed Mary | Scrophulariaceae | |
| Collomia | trumpet | Polemoniaceae | |
| Collomia grandiflora | grand collomia | Polemoniaceae | |
| Collomia linearis | tiny trumpet | Polemoniaceae | |
| Cologania | cologania | Fabaceae | |
| Cologania angustifolia | longleaf cologania | Fabaceae | |
| Cologania obovata | Lemmon's cologania | Fabaceae | |
| Cologania pallida | pale cologania | Fabaceae | |
| Colubrina | nakedwood | Rhamnaceae | |
| Colubrina californica | Las Animas nakedwood | Rhamnaceae | |
| Comandra | bastard toadflax | Santalaceae | |
| Comandra umbellata | bastard toadflax | Santalaceae | |
| Comandra umbellata ssp. californica | California bastard toadflax | Santalaceae | |
| Comandra umbellata ssp. pallida | pale bastard toadflax | Santalaceae | |
| Commelina | dayflower | Commelinaceae | |
| Commelina dianthifolia | birdbill dayflower | Commelinaceae | |
| Commelina dianthifolia var. dianthifolia | birdbill dayflower | Commelinaceae | |
| Commelina dianthifolia var. longispatha | birdbill dayflower | Commelinaceae | |
| Commelina erecta | whitemouth dayflower | Commelinaceae | |
| Commelina erecta var. angustifolia | whitemouth dayflower | Commelinaceae | |
| Commelina erecta var. deamiana | whitemouth dayflower | Commelinaceae | |
| Commelina erecta var. erecta | whitemouth dayflower | Commelinaceae | |
| Condalia | snakewood | Rhamnaceae | |
| Condalia correllii | Correll's snakewood | Rhamnaceae | |
| Condalia ericoides | javelina bush | Rhamnaceae | |
| Condalia globosa | bitter snakewood | Rhamnaceae | |
| Condalia globosa var. pubescens | bitter snakewood | Rhamnaceae | |
| Condalia warnockii | Warnock's snakewood | Rhamnaceae | |
| Condalia warnockii var. kearneyana | Kearney's snakewood | Rhamnaceae | |
| Conioselinum | hemlockparsley | Apiaceae | |
| Conioselinum mexicanum | Mexican hemlockparsley | Apiaceae | |
| Conioselinum scopulorum | Rocky Mountain hemlockparsley | Apiaceae | |
| Conium | poison hemlock | Apiaceae | |
| Conium maculatum | poison hemlock | Apiaceae | |
| Conoclinium | thoroughwort | Asteraceae | |
| Conoclinium greggii | palmleaf thoroughwort | Asteraceae | |
| Conopholis | cancer-root | Orobanchaceae | |
| Conopholis alpina | alpine cancer-root | Orobanchaceae | |
| Conopholis alpina var. mexicana | Mexican cancer-root | Orobanchaceae | |
| Conringia | hare's ear mustard | Brassicaceae | |
| Conringia orientalis | hare's ear mustard | Brassicaceae | |
| Consolida | knight's-spur | Ranunculaceae | |
| Consolida ajacis | doubtful knight's-spur | Ranunculaceae | |
| Convolvulus | bindweed | Convolvulaceae | |
| Convolvulus arvensis | field bindweed | Convolvulaceae | |
| Convolvulus equitans | Texas bindweed | Convolvulaceae | |
| Conyza | horseweed | Asteraceae | |
| Conyza bonariensis | asthmaweed | Asteraceae | |
| Conyza canadensis | Canadian horseweed | Asteraceae | |
| Conyza canadensis var. canadensis | Canadian horseweed | Asteraceae | |
| Conyza canadensis var. glabrata | Canadian horseweed | Asteraceae | |
| Conyza canadensis var. pusilla | Canadian horseweed | Asteraceae | |
| Corallorhiza | coralroot | Orchidaceae | |
| Corallorhiza maculata | summer coralroot | Orchidaceae | |
| Corallorhiza maculata var. maculata | summer coralroot | Orchidaceae | |
| Corallorhiza maculata var. occidentalis | summer coralroot | Orchidaceae | |
| Corallorhiza striata | hooded coralroot | Orchidaceae | |
| Corallorhiza striata var. vreelandii | Vreeland's coralroot | Orchidaceae | |
| Corallorhiza wisteriana | spring coralroot | Orchidaceae | |
| Corchorus | corchorus | Tiliaceae | |
| Corchorus hirtus | Orinoco jute | Tiliaceae | |
| Cordia | cordia | Boraginaceae | |
| Cordia parvifolia | small-leaf geigertree | Boraginaceae | |
| Cordylanthus | bird's-beak | Scrophulariaceae | |
| Cordylanthus laxiflorus | nodding bird's-beak | Scrophulariaceae | |
| Cordylanthus nevinii | Nevin's bird's-beak | Scrophulariaceae | |
| Cordylanthus parviflorus | purple bird's-beak | Scrophulariaceae | |
| Cordylanthus wrightii | Wright's bird's beak | Scrophulariaceae | |
| Cordylanthus wrightii ssp. kaibabensis | Kaibab bird's beak | Scrophulariaceae | |
| Cordylanthus wrightii ssp. tenuifolius | Wright's bird's beak | Scrophulariaceae | |
| Cordylanthus wrightii ssp. wrightii | Wright's bird's beak | Scrophulariaceae | |
| Coreocarpus | coreocarpus | Asteraceae | |
| Coreocarpus arizonicus | little lemonhead | Asteraceae | |
| Coreopsis | tickseed | Asteraceae | |
| Coreopsis californica | California tickseed | Asteraceae | |
| Coreopsis californica var. newberryi | Newberry's tickseed | Asteraceae | |
| Coreopsis tinctoria | golden tickseed | Asteraceae | |
| Coreopsis tinctoria var. atkinsoniana | Atkinson's tickseed | Asteraceae | |
| Coreopsis tinctoria var. tinctoria | golden tickseed | Asteraceae | |
| Coriandrum | coriander | Apiaceae | |
| Coriandrum sativum | coriander | Apiaceae | |
| Corispermum | bugseed | Chenopodiaceae | |
| Corispermum americanum | American bugseed | Chenopodiaceae | |
| Corispermum americanum var. americanum | American bugseed | Chenopodiaceae | |
| Corispermum americanum var. rydbergii | American bugseed | Chenopodiaceae | |
| Corispermum welshii | Welsh's bugseed | Chenopodiaceae | |
| Cornus | dogwood | Cornaceae | |
| Cornus sericea | redosier dogwood | Cornaceae | |
| Cornus sericea ssp. sericea | redosier dogwood | Cornaceae | |
| Coronopus | swinecress | Brassicaceae | |
| Coronopus didymus | lesser swinecress | Brassicaceae | |
| Corydalis | fumewort | Fumariaceae | |
| Corydalis aurea | scrambled eggs | Fumariaceae | |
| Corydalis curvisiliqua | curvepod fumewort | Fumariaceae | |
| Corydalis curvisiliqua ssp. occidentalis | curvepod fumewort | Fumariaceae | |
| Coryphantha | beehive cactus | Cactaceae | |
| Coryphantha recurvata | Santa Cruz beehive cactus | Cactaceae | |
| Coryphantha robustispina | long-tubercle beehive cactus | Cactaceae | |
| Coryphantha robustispina ssp. robustispina | long-tubercle beehive cactus | Cactaceae | |
| Coryphantha robustispina ssp. scheeri | Scheer's beehive cactus | Cactaceae | |
| Coryphantha robustispina ssp. uncinata | Scheer's beehive cactus | Cactaceae | |
| Cosmos | cosmos | Asteraceae | |
| Cosmos bipinnatus | garden cosmos | Asteraceae | |
| Cosmos parviflorus | southwestern cosmos | Asteraceae | |
| Cottea | cotta grass | Poaceae | |
| Cottea pappophoroides | cotta grass | Poaceae | |
| Cotula | waterbuttons | Asteraceae | |
| Cotula australis | Australian waterbuttons | Asteraceae | |
| Cotula coronopifolia | common brassbuttons | Asteraceae | |
| Coursetia | babybonnets | Fabaceae | |
| Coursetia caribaea | anil falso | Fabaceae | |
| Coursetia caribaea var. sericea | anil falso | Fabaceae | |
| Coursetia glabella | smooth babybonnets | Fabaceae | |
| Coursetia glandulosa | rosary babybonnets | Fabaceae | |
| Crassula | pygmyweed | Crassulaceae | |
| Crassula aquatica | water pygmyweed | Crassulaceae | |
| Crassula connata | sand pygmyweed | Crassulaceae | |
| Crassula connata var. erectoides | sand pygmyweed | Crassulaceae | |
| Crassula connata var. eremica | sand pygmyweed | Crassulaceae | |
| Crassula connata var. subsimplex | sand pygmyweed | Crassulaceae | |
| Crassula viridis | pricklyseed pygmyweed | Crassulaceae | |
| Crataegus | hawthorn | Rosaceae | |
| Crataegus erythropoda | cerro hawthorn | Rosaceae | |
| Crataegus rivularis | river hawthorn | Rosaceae | |
| Crataegus succulenta | fleshy hawthorn | Rosaceae | |
| Crepis | hawksbeard | Asteraceae | |
| Crepis acuminata | tapertip hawksbeard | Asteraceae | |
| Crepis acuminata ssp. acuminata | tapertip hawksbeard | Asteraceae | |
| Crepis intermedia | limestone hawksbeard | Asteraceae | |
| Crepis occidentalis | largeflower hawksbeard | Asteraceae | |
| Crepis occidentalis ssp. costata | largeflower hawksbeard | Asteraceae | |
| Crepis occidentalis ssp. occidentalis | largeflower hawksbeard | Asteraceae | |
| Crepis runcinata | fiddleleaf hawksbeard | Asteraceae | |
| Crepis runcinata ssp. barberi | Barber's hawksbeard | Asteraceae | |
| Crepis runcinata ssp. glauca | fiddleleaf hawksbeard | Asteraceae | |
| Cressa | alkaliweed | Convolvulaceae | |
| Cressa truxillensis | spreading alkaliweed | Convolvulaceae | |
| Crossosoma | rockflower | Crossosomataceae | |
| Crossosoma bigelovii | ragged rockflower | Crossosomataceae | |
| Crossosoma bigelovii var. bigelovii | ragged rockflower | Crossosomataceae | |
| Crossosoma bigelovii var. glaucum | ragged rockflower | Crossosomataceae | |
| Crotalaria | rattlebox | Fabaceae | |
| Crotalaria pumila | low rattlebox | Fabaceae | |
| Crotalaria sagittalis | arrowhead rattlebox | Fabaceae | |
| Croton | croton | Euphorbiaceae | |
| Croton californicus | California croton | Euphorbiaceae | |
| Croton californicus var. californicus | California croton | Euphorbiaceae | |
| Croton californicus var. tenuis | California croton | Euphorbiaceae | |
| Croton ciliatoglandulifer | Mexican croton | Euphorbiaceae | |
| Croton fruticulosus | bush croton | Euphorbiaceae | |
| Croton lindheimerianus | threeseed croton | Euphorbiaceae | |
| Croton lindheimerianus var. lindheimerianus | threeseed croton | Euphorbiaceae | |
| Croton lindheimerianus var. tharpii | Tharp's croton | Euphorbiaceae | |
| Croton monanthogynus | prairie tea | Euphorbiaceae | |
| Croton pottsii | leatherweed | Euphorbiaceae | |
| Croton pottsii var. pottsii | leatherweed | Euphorbiaceae | |
| Croton setigerus | dove weed | Euphorbiaceae | |
| Croton sonorae | Sonoran croton | Euphorbiaceae | |
| Croton texensis | Texas croton | Euphorbiaceae | |
| Croton texensis var. texensis | Texas croton | Euphorbiaceae | |
| Croton texensis var. utahensis | Utah croton | Euphorbiaceae | |
| Croton wigginsii | Wiggins' croton | Euphorbiaceae | |
| Crusea | mountain saucerflower | Rubiaceae | |
| Crusea diversifolia | mountain saucerflower | Rubiaceae | |
| Crypsis | pricklegrass | Poaceae | |
| Crypsis schoenoides | swamp pricklegrass | Poaceae | |
| Cryptantha | cryptantha | Boraginaceae | |
| Cryptantha abata | dentnut cryptantha | Boraginaceae | |
| Cryptantha albida | New Mexico cryptantha | Boraginaceae | |
| Cryptantha angustifolia | Panamint cryptantha | Boraginaceae | |
| Cryptantha atwoodii | Atwood's cryptantha | Boraginaceae | |
| Cryptantha bakeri | Baker's cryptantha | Boraginaceae | |
| Cryptantha barbigera | bearded cryptantha | Boraginaceae | |
| Cryptantha capitata | capitate cryptantha | Boraginaceae | |
| Cryptantha cinerea | James' cryptantha | Boraginaceae | |
| Cryptantha cinerea var. arenicola | James' cryptantha | Boraginaceae | |
| Cryptantha cinerea var. cinerea | James' cryptantha | Boraginaceae | |
| Cryptantha cinerea var. jamesii | James' cryptantha | Boraginaceae | |
| Cryptantha cinerea var. pustulosa | James' cryptantha | Boraginaceae | |
| Cryptantha circumscissa | cushion cryptantha | Boraginaceae | |
| Cryptantha circumscissa var. circumscissa | cushion cryptantha | Boraginaceae | |
| Cryptantha confertiflora | basin yellow cryptantha | Boraginaceae | |
| Cryptantha costata | ribbed cryptantha | Boraginaceae | |
| Cryptantha crassisepala | thicksepal cryptantha | Boraginaceae | |
| Cryptantha crassisepala var. elachantha | thicksepal cryptantha | Boraginaceae | |
| Cryptantha decipiens | gravelbar cryptantha | Boraginaceae | |
| Cryptantha dumetorum | bushloving cryptantha | Boraginaceae | |
| Cryptantha fendleri | sanddune cryptantha | Boraginaceae | |
| Cryptantha flava | Brenda's yellow cryptantha | Boraginaceae | |
| Cryptantha flavoculata | roughseed cryptantha | Boraginaceae | |
| Cryptantha fulvocanescens | tawny cryptantha | Boraginaceae | |
| Cryptantha fulvocanescens var. fulvocanescens | tawny cryptantha | Boraginaceae | |
| Cryptantha fulvocanescens var. nitida | tawny cryptantha | Boraginaceae | |
| Cryptantha ganderi | Gander's cryptantha | Boraginaceae | |
| Cryptantha gracilis | narrowstem cryptantha | Boraginaceae | |
| Cryptantha holoptera | winged cryptantha | Boraginaceae | |
| Cryptantha humilis | roundspike cryptantha | Boraginaceae | |
| Cryptantha intermedia | Clearwater cryptantha | Boraginaceae | |
| Cryptantha maritima | Guadalupe cryptantha | Boraginaceae | |
| Cryptantha maritima var. maritima | Guadalupe cryptantha | Boraginaceae | |
| Cryptantha maritima var. pilosa | Guadalupe cryptantha | Boraginaceae | |
| Cryptantha micrantha | redroot cryptantha | Boraginaceae | |
| Cryptantha micrantha var. micrantha | redroot cryptantha | Boraginaceae | |
| Cryptantha muricata | pointed cryptantha | Boraginaceae | |
| Cryptantha nevadensis | Nevada cryptantha | Boraginaceae | |
| Cryptantha nevadensis var. nevadensis | Nevada cryptantha | Boraginaceae | |
| Cryptantha nevadensis var. rigida | Nevada cryptantha | Boraginaceae | |
| Cryptantha osterhoutii | Osterhout's cryptantha | Boraginaceae | |
| Cryptantha pterocarya | wingnut cryptantha | Boraginaceae | |
| Cryptantha pterocarya var. cycloptera | wingnut cryptantha | Boraginaceae | |
| Cryptantha pterocarya var. pterocarya | wingnut cryptantha | Boraginaceae | |
| Cryptantha pterocarya var. stenoloba | wingnut cryptantha | Boraginaceae | |
| Cryptantha pusilla | low cryptantha | Boraginaceae | |
| Cryptantha racemosa | bushy cryptantha | Boraginaceae | |
| Cryptantha recurvata | curvenut cryptantha | Boraginaceae | |
| Cryptantha semiglabra | smooth cryptantha | Boraginaceae | |
| Cryptantha setosissima | bristly cryptantha | Boraginaceae | |
| Cryptantha utahensis | scented cryptantha | Boraginaceae | |
| Cryptantha virginensis | Virgin River cryptantha | Boraginaceae | |
| Cryptogramma | rockbrake | Pteridaceae | |
| Cryptogramma acrostichoides | American rockbrake | Pteridaceae | |
| Cucurbita | gourd | Cucurbitaceae | |
| Cucurbita digitata | fingerleaf gourd | Cucurbitaceae | |
| Cucurbita foetidissima | Missouri gourd | Cucurbitaceae | |
| Cucurbita palmata | coyote gourd | Cucurbitaceae | |
| Cuphea | waxweed | Lythraceae | |
| Cuphea wrightii | Wright's waxweed | Lythraceae | |
| Cupressus | cypress | Cupressaceae | |
| Cupressus arizonica | Arizona cypress | Cupressaceae | |
| Cupressus arizonica ssp. arizonica | Arizona cypress | Cupressaceae | |
| Cuscuta | dodder | Cuscutaceae | |
| Cuscuta applanata | Gila River dodder | Cuscutaceae | |
| Cuscuta californica | chaparral dodder | Cuscutaceae | |
| Cuscuta californica var. californica | chaparral dodder | Cuscutaceae | |
| Cuscuta cephalanthi | buttonbush dodder | Cuscutaceae | |
| Cuscuta coryli | hazel dodder | Cuscutaceae | |
| Cuscuta dentatasquamata | los pinitos dodder | Cuscutaceae | |
| Cuscuta denticulata | desert dodder | Cuscutaceae | |
| Cuscuta denticulata var. denticulata | desert dodder | Cuscutaceae | |
| Cuscuta erosa | Sonoran dodder | Cuscutaceae | |
| Cuscuta gronovii | scaldweed | Cuscutaceae | |
| Cuscuta gronovii var. gronovii | scaldweed | Cuscutaceae | |
| Cuscuta indecora | bigseed alfalfa dodder | Cuscutaceae | |
| Cuscuta indecora var. indecora | bigseed alfalfa dodder | Cuscutaceae | |
| Cuscuta indecora var. neuropetala | bigseed dodder | Cuscutaceae | |
| Cuscuta mitriformis | Cochise dodder | Cuscutaceae | |
| Cuscuta odontolepis | Santa Rita Mountain dodder | Cuscutaceae | |
| Cuscuta pentagona | fiveangled dodder | Cuscutaceae | |
| Cuscuta pentagona var. pentagona | fiveangled dodder | Cuscutaceae | |
| Cuscuta potosina | globe dodder | Cuscutaceae | |
| Cuscuta potosina var. globifera | globe dodder | Cuscutaceae | |
| Cuscuta salina | saltmarsh dodder | Cuscutaceae | |
| Cuscuta salina var. papillata | goldenthread | Cuscutaceae | |
| Cuscuta salina var. salina | saltmarsh dodder | Cuscutaceae | |
| Cuscuta tuberculata | tubercle dodder | Cuscutaceae | |
| Cuscuta umbellata | flatglobe dodder | Cuscutaceae | |
| Cuscuta warneri | Warner's dodder | Cuscutaceae | |
| Cyclachaena | Asteraceae | ||
| Cyclachaena xanthifolia | giant sumpweed | Asteraceae | |
| Cycladenia | waxydogbane | Apocynaceae | |
| Cycladenia humilis | Sacramento waxydogbane | Apocynaceae | |
| Cycladenia humilis var. jonesii | Jones' waxydogbane | Apocynaceae | |
| Cyclanthera | cyclanthera | Cucurbitaceae | |
| Cyclanthera dissecta | cutleaf cyclanthera | Cucurbitaceae | |
| Cycloloma | cycloloma | Chenopodiaceae | |
| Cycloloma atriplicifolium | winged pigweed | Chenopodiaceae | |
| Cyclospermum | marsh parsley | Apiaceae | |
| Cyclospermum leptophyllum | marsh parsley | Apiaceae | |
| Cylindropuntia | Cactaceae | ||
| Cylindropuntia abysii | Peach Springs canyon cholla | Cactaceae | |
| Cylindropuntia acanthocarpa | buck-horn cholla | Cactaceae | |
| Cylindropuntia acanthocarpa var. acanthocarpa | buckhorn cholla | Cactaceae | |
| Cylindropuntia acanthocarpa var. coloradensis | Colorado buckhorn cholla | Cactaceae | |
| Cylindropuntia acanthocarpa var. major | buckhorn cholla | Cactaceae | |
| Cylindropuntia acanthocarpa var. thornberi | Thornber's buckhorn cholla | Cactaceae | |
| Cylindropuntia arbuscula | Arizona pencil cholla | Cactaceae | |
| Cylindropuntia bigelovii | teddybear cholla | Cactaceae | |
| Cylindropuntia congesta | Cactaceae | ||
| Cylindropuntia echinocarpa | Wiggins' cholla | Cactaceae | |
| Cylindropuntia fulgida | jumping cholla | Cactaceae | |
| Cylindropuntia fulgida var. fulgida | jumping cholla | Cactaceae | |
| Cylindropuntia fulgida var. mamillata | jumping cholla | Cactaceae | |
| Cylindropuntia imbricata | tree cholla | Cactaceae | |
| Cylindropuntia imbricata var. imbricata | tree cholla | Cactaceae | |
| Cylindropuntia kelvinensis | Cactaceae | ||
| Cylindropuntia leptocaulis | Christmas cactus | Cactaceae | |
| Cylindropuntia multigeniculata | Blue Diamond cholla | Cactaceae | |
| Cylindropuntia ramosissima | branched pencil cholla | Cactaceae | |
| Cylindropuntia spinosior | walkingstick cactus | Cactaceae | |
| Cylindropuntia tetracantha | Tucson pricklypear | Cactaceae | |
| Cylindropuntia versicolor | staghorn cholla | Cactaceae | |
| Cylindropuntia vivipara | Cactaceae | ||
| Cylindropuntia whipplei | Whipple cholla | Cactaceae | |
| Cymopterus | springparsley | Apiaceae | |
| Cymopterus acaulis | plains springparsley | Apiaceae | |
| Cymopterus acaulis var. fendleri | Fendler's springparsley | Apiaceae | |
| Cymopterus beckii | featherleaf springparsley | Apiaceae | |
| Cymopterus bulbosus | bulbous springparsley | Apiaceae | |
| Cymopterus constancei | Constance's springparsley | Apiaceae | |
| Cymopterus jonesii | Jones' springparsley | Apiaceae | |
| Cymopterus megacephalus | largeleaf springparsley | Apiaceae | |
| Cymopterus multinervatus | purplenerve springparsley | Apiaceae | |
| Cymopterus newberryi | sweetroot springparsley | Apiaceae | |
| Cymopterus purpurascens | widewing springparsley | Apiaceae | |
| Cymopterus purpureus | purple springparsley | Apiaceae | |
| Cynanchum | swallow-wort | Asclepiadaceae | |
| Cynanchum arizonicum | Arizona swallow-wort | Asclepiadaceae | |
| Cynanchum ligulatum | Mexican swallow-wort | Asclepiadaceae | |
| Cynanchum utahense | Utah swallow-wort | Asclepiadaceae | |
| Cynanchum wigginsii | Wiggins' swallow-wort | Asclepiadaceae | |
| Cynara | cynara | Asteraceae | |
| Cynara scolymus | globe artichoke | Asteraceae | |
| Cynodon | Bermudagrass | Poaceae | |
| Cynodon dactylon | Bermudagrass | Poaceae | |
| Cynoglossum | hound's tongue | Boraginaceae | |
| Cynoglossum officinale | gypsyflower | Boraginaceae | |
| Cyperus | flatsedge | Cyperaceae | |
| Cyperus acuminatus | tapertip flatsedge | Cyperaceae | |
| Cyperus aggregatus | inflatedscale flatsedge | Cyperaceae | |
| Cyperus amabilis | foothill flatsedge | Cyperaceae | |
| Cyperus dentoniae | hairy flatsedge | Cyperaceae | |
| Cyperus difformis | variable flatsedge | Cyperaceae | |
| Cyperus dipsaceus | Wright's flatsedge | Cyperaceae | |
| Cyperus erythrorhizos | redroot flatsedge | Cyperaceae | |
| Cyperus esculentus | yellow nutsedge | Cyperaceae | |
| Cyperus esculentus var. leptostachyus | yellow nutsedge | Cyperaceae | |
| Cyperus fendlerianus | Fendler's flatsedge | Cyperaceae | |
| Cyperus flavicomus | whiteedge flatsedge | Cyperaceae | |
| Cyperus hermaphroditus | hermaphrodite flatsedge | Cyperaceae | |
| Cyperus hypopitys | pine flatsedge | Cyperaceae | |
| Cyperus involucratus | unbrella plant | Cyperaceae | |
| Cyperus laevigatus | smooth flatsedge | Cyperaceae | |
| Cyperus manimae | spectacular flatsedge | Cyperaceae | |
| Cyperus manimae var. asperrimus | spectacular flatsedge | Cyperaceae | |
| Cyperus mutisii | Mutis' flatsedge | Cyperaceae | |
| Cyperus niger | black flatsedge | Cyperaceae | |
| Cyperus odoratus | fragrant flatsedge | Cyperaceae | |
| Cyperus pallidicolor | pallid flatsedge | Cyperaceae | |
| Cyperus parishii | Parish's flatsedge | Cyperaceae | |
| Cyperus retroflexus | oneflower flatsedge | Cyperaceae | |
| Cyperus rotundus | nutgrass | Cyperaceae | |
| Cyperus schweinitzii | Schweinitz's flatsedge | Cyperaceae | |
| Cyperus seslerioides | Texas flatsedge | Cyperaceae | |
| Cyperus spectabilis | spectacular flatsedge | Cyperaceae | |
| Cyperus sphaerolepis | Rusby's flatsedge | Cyperaceae | |
| Cyperus squarrosus | bearded flatsedge | Cyperaceae | |
| Cyperus strigosus | strawcolored flatsedge | Cyperaceae | |
| Cyperus tetragonus | fourangle flatsedge | Cyperaceae | |
| Cypripedium | lady's slipper | Orchidaceae | |
| Cypripedium parviflorum | lesser yellow lady's slipper | Orchidaceae | |
| Cypripedium parviflorum var. pubescens | greater yellow lady's slipper | Orchidaceae | |
| Cypselea | cypselea | Aizoaceae | |
| Cypselea humifusa | panal | Aizoaceae | |
| Cystopteris | bladderfern | Dryopteridaceae | |
| Cystopteris bulbifera | bulblet bladderfern | Dryopteridaceae | |
| Cystopteris fragilis | brittle bladderfern | Dryopteridaceae | |
| Cystopteris reevesiana | Reeves' bladderfern | Dryopteridaceae | |
| Cystopteris tenuis | upland brittle bladderfern | Dryopteridaceae | |
| Cystopteris utahensis | Utah bladderfern | Dryopteridaceae | |
| D | |||
| Dactylis | orchardgrass | Poaceae | |
| Dactylis glomerata | orchardgrass | Poaceae | |
| Dactylis glomerata ssp. glomerata | orchardgrass | Poaceae | |
| Dactyloctenium | crowfoot grass | Poaceae | |
| Dactyloctenium aegyptium | Egyptian grass | Poaceae | |
| Dactyloctenium radulans | buttongrass | Poaceae | |
| Dactylorhiza | keyflower | Orchidaceae | |
| Dactylorhiza viridis | longbract frog orchid | Orchidaceae | |
| Dalea | prairie clover | Fabaceae | |
| Dalea albiflora | whiteflower prairie clover | Fabaceae | |
| Dalea aurea | golden prairie clover | Fabaceae | |
| Dalea bicolor | silver prairie clover | Fabaceae | |
| Dalea bicolor var. argyrea | silver prairie clover | Fabaceae | |
| Dalea brachystachya | Fort Bowie prairie clover | Fabaceae | |
| Dalea candida | white prairie clover | Fabaceae | |
| Dalea candida var. oligophylla | white prairie clover | Fabaceae | |
| Dalea exigua | Chihuahuan prairie clover | Fabaceae | |
| Dalea exserta | Mexican prairie clover | Fabaceae | |
| Dalea filiformis | Sonoran prairie clover | Fabaceae | |
| Dalea flavescens | Canyonlands prairie clover | Fabaceae | |
| Dalea formosa | featherplume | Fabaceae | |
| Dalea grayi | Gray's prairie clover | Fabaceae | |
| Dalea jamesii | James' prairie clover | Fabaceae | |
| Dalea lachnostachys | glandleaf prairie clover | Fabaceae | |
| Dalea lanata | woolly prairie clover | Fabaceae | |
| Dalea lanata var. terminalis | woolly prairie clover | Fabaceae | |
| Dalea leporina | foxtail prairie clover | Fabaceae | |
| Dalea lumholtzii | Lumholtz's prairie clover | Fabaceae | |
| Dalea mollis | hairy prairie clover | Fabaceae | |
| Dalea mollissima | soft prairie clover | Fabaceae | |
| Dalea nana | dwarf prairie clover | Fabaceae | |
| Dalea nana var. carnescens | dwarf prairie clover | Fabaceae | |
| Dalea nana var. nana | dwarf prairie clover | Fabaceae | |
| Dalea neomexicana | downy prairie clover | Fabaceae | |
| Dalea neomexicana var. neomexicana | downy prairie clover | Fabaceae | |
| Dalea pogonathera | bearded prairie clover | Fabaceae | |
| Dalea pogonathera var. pogonathera | bearded prairie clover | Fabaceae | |
| Dalea polygonoides | sixweeks prairie clover | Fabaceae | |
| Dalea pringlei | Pringle's prairie clover | Fabaceae | |
| Dalea pulchra | Santa Catalina prairie clover | Fabaceae | |
| Dalea purpurea | purple prairie clover | Fabaceae | |
| Dalea purpurea var. purpurea | purple prairie clover | Fabaceae | |
| Dalea searlsiae | Searls' prairie clover | Fabaceae | |
| Dalea tentaculoides | Gentry's indigobush | Fabaceae | |
| Dalea tenuifolia | slimleaf prairie clover | Fabaceae | |
| Dalea urceolata | pineforest prairie clover | Fabaceae | |
| Dalea versicolor | oakwoods prairie clover | Fabaceae | |
| Dalea versicolor var. sessilis | oakwoods prairie clover | Fabaceae | |
| Dalea versicolor var. versicolor | oakwoods prairie clover | Fabaceae | |
| Dalea wrightii | Wright's prairie clover | Fabaceae | |
| Danthonia | oatgrass | Poaceae | |
| Danthonia californica | California oatgrass | Poaceae | |
| Danthonia intermedia | timber oatgrass | Poaceae | |
| Danthonia spicata | poverty oatgrass | Poaceae | |
| Dasiphora | shrubby cinquefoil | Rosaceae | |
| Dasiphora fruticosa | shrubby cinquefoil | Rosaceae | |
| Dasiphora fruticosa ssp. floribunda | shrubby cinquefoil | Rosaceae | |
| Dasylirion | sotol | Liliaceae | |
| Dasylirion wheeleri | common sotol | Liliaceae | |
| Dasyochloa | woollygrass | Poaceae | |
| Dasyochloa pulchella | low woollygrass | Poaceae | |
| Datura | jimsonweed | Solanaceae | |
| Datura discolor | desert thorn-apple | Solanaceae | |
| Datura inoxia | pricklyburr | Solanaceae | |
| Datura quercifolia | Chinese thorn-apple | Solanaceae | |
| Datura stramonium | jimsonweed | Solanaceae | |
| Datura wrightii | sacred thorn-apple | Solanaceae | |
| Daucus | wild carrot | Apiaceae | |
| Daucus carota | Queen Anne's lace | Apiaceae | |
| Daucus pusillus | American wild carrot | Apiaceae | |
| Delphinium | larkspur | Ranunculaceae | |
| Delphinium andesicola | Chiricahua Mountain larkspur | Ranunculaceae | |
| Delphinium barbeyi | subalpine larkspur | Ranunculaceae | |
| Delphinium confertiflorum | Ranunculaceae | ||
| Delphinium geraniifolium | Clark Valley larkspur | Ranunculaceae | |
| Delphinium glaucum | Sierra larkspur | Ranunculaceae | |
| Delphinium nuttallianum | twolobe larkspur | Ranunculaceae | |
| Delphinium parishii | desert larkspur | Ranunculaceae | |
| Delphinium parishii ssp. parishii | Parish's larkspur | Ranunculaceae | |
| Delphinium scaposum | tall mountain larkspur | Ranunculaceae | |
| Delphinium scopulorum | Rocky Mountain larkspur | Ranunculaceae | |
| Delphinium wootonii | Organ Mountain larkspur | Ranunculaceae | |
| Deschampsia | hairgrass | Poaceae | |
| Deschampsia cespitosa | tufted hairgrass | Poaceae | |
| Deschampsia danthonioides | annual hairgrass | Poaceae | |
| Deschampsia elongata | slender hairgrass | Poaceae | |
| Descurainia | tansymustard | Brassicaceae | |
| Descurainia californica | Sierra tansymustard | Brassicaceae | |
| Descurainia incana | mountain tansymustard | Brassicaceae | |
| Descurainia incana ssp. incisa | mountain tansymustard | Brassicaceae | |
| Descurainia incana ssp. viscosa | mountain tansymustard | Brassicaceae | |
| Descurainia obtusa | blunt tansymustard | Brassicaceae | |
| Descurainia obtusa ssp. adenophora | blunt tansymustard | Brassicaceae | |
| Descurainia obtusa ssp. obtusa | blunt tansymustard | Brassicaceae | |
| Descurainia pinnata | western tansymustard | Brassicaceae | |
| Descurainia pinnata ssp. filipes | western tansymustard | Brassicaceae | |
| Descurainia pinnata ssp. glabra | western tansymustard | Brassicaceae | |
| Descurainia pinnata ssp. halictorum | western tansymustard | Brassicaceae | |
| Descurainia pinnata ssp. ochroleuca | western tansymustard | Brassicaceae | |
| Descurainia pinnata ssp. paysonii | Payson's tansymustard | Brassicaceae | |
| Descurainia sophia | herb sophia | Brassicaceae | |
| Desmanthus | bundleflower | Fabaceae | |
| Desmanthus bicornutus | two-horn bundleflower | Fabaceae | |
| Desmanthus cooleyi | Cooley's bundleflower | Fabaceae | |
| Desmanthus covillei | Coville's bundleflower | Fabaceae | |
| Desmanthus glandulosus | glandular bundleflower | Fabaceae | |
| Desmodium | ticktrefoil | Fabaceae | |
| Desmodium arizonicum | Arizona ticktrefoil | Fabaceae | |
| Desmodium batocaulon | San Pedro ticktrefoil | Fabaceae | |
| Desmodium cinerascens | spiked ticktrefoil | Fabaceae | |
| Desmodium grahamii | Graham's ticktrefoil | Fabaceae | |
| Desmodium gramineum | grassleaf ticktrefoil | Fabaceae | |
| Desmodium intortum | greenleaf ticktrefoil | Fabaceae | |
| Desmodium metcalfei | Metcalfe's ticktrefoil | Fabaceae | |
| Desmodium neomexicanum | New Mexico ticktrefoil | Fabaceae | |
| Desmodium procumbens | western trailing ticktrefoil | Fabaceae | |
| Desmodium procumbens var. exiguum | western trailing ticktrefoil | Fabaceae | |
| Desmodium psilocarpum | Santa Cruz Island ticktrefoil | Fabaceae | |
| Desmodium psilophyllum | simpleleaf ticktrefoil | Fabaceae | |
| Desmodium retinens | Santa Rita Mountain ticktrefoil | Fabaceae | |
| Desmodium rosei | Rose's ticktrefoil | Fabaceae | |
| Desmodium scopulorum | Sonoran ticktrefoil | Fabaceae | |
| Dichanthelium | rosette grass | Poaceae | |
| Dichanthelium acuminatum | tapered rosette grass | Poaceae | |
| Dichanthelium acuminatum var. acuminatum | tapered rosette grass | Poaceae | |
| Dichanthelium acuminatum var. fasciculatum | western panicgrass | Poaceae | |
| Dichanthelium oligosanthes | Heller's rosette grass | Poaceae | |
| Dichanthelium oligosanthes var. scribnerianum | Scribner's rosette grass | Poaceae | |
| Dichelostemma | snakelily | Liliaceae | |
| Dichelostemma capitatum | bluedicks | Liliaceae | |
| Dichelostemma capitatum ssp. capitatum | bluedicks | Liliaceae | |
| Dichelostemma capitatum ssp. pauciflorum | bluedicks | Liliaceae | |
| Dichondra | ponysfoot | Convolvulaceae | |
| Dichondra argentea | silver ponysfoot | Convolvulaceae | |
| Dichondra brachypoda | New Mexico ponysfoot | Convolvulaceae | |
| Dichondra micrantha | Asian ponysfoot | Convolvulaceae | |
| Dichondra sericea | silverleaf ponysfoot | Convolvulaceae | |
| Dicliptera | foldwing | Acanthaceae | |
| Dicliptera resupinata | Arizona foldwing | Acanthaceae | |
| Dicoria | twinbugs | Asteraceae | |
| Dicoria canescens | desert twinbugs | Asteraceae | |
| Dicoria canescens ssp. brandegeei | desert twinbugs | Asteraceae | |
| Dicoria canescens ssp. canescens | desert twinbugs | Asteraceae | |
| Digitaria | crabgrass | Poaceae | |
| Digitaria californica | Arizona cottontop | Poaceae | |
| Digitaria ciliaris | southern crabgrass | Poaceae | |
| Digitaria eriantha | digitgrass | Poaceae | |
| Digitaria insularis | sourgrass | Poaceae | |
| Digitaria ischaemum | smooth crabgrass | Poaceae | |
| Digitaria pubiflora | Carolina crabgrass | Poaceae | |
| Digitaria sanguinalis | hairy crabgrass | Poaceae | |
| Dimorphocarpa | spectaclepod | Brassicaceae | |
| Dimorphocarpa pinnatifida | tansy spectaclepod | Brassicaceae | |
| Dimorphocarpa wislizeni | touristplant | Brassicaceae | |
| Dimorphotheca | Cape marigold | Asteraceae | |
| Dimorphotheca sinuata | glandular Cape marigold | Asteraceae | |
| Diodia | buttonweed | Rubiaceae | |
| Diodia teres | poorjoe | Rubiaceae | |
| Diodia teres var. angustata | poorjoe | Rubiaceae | |
| Diodia teres var. teres | poorjoe | Rubiaceae | |
| Diphysa | diphysa | Fabaceae | |
| Diphysa thurberi | Thurber's diphysa | Fabaceae | |
| Diplotaxis | wallrocket | Brassicaceae | |
| Diplotaxis muralis | annual wallrocket | Brassicaceae | |
| Diplotaxis tenuifolia | perennial wallrocket | Brassicaceae | |
| Dipsacus | teasel | Dipsacaceae | |
| Dipsacus fullonum | Fuller's teasel | Dipsacaceae | |
| Distichlis | saltgrass | Poaceae | |
| Distichlis spicata | saltgrass | Poaceae | |
| Dithyrea | shieldpod | Brassicaceae | |
| Dithyrea californica | California shieldpod | Brassicaceae | |
| Dodecatheon | shootingstar | Primulaceae | |
| Dodecatheon alpinum | alpine shootingstar | Primulaceae | |
| Dodecatheon alpinum ssp. majus | alpine shootingstar | Primulaceae | |
| Dodecatheon dentatum | white shootingstar | Primulaceae | |
| Dodecatheon dentatum ssp. ellisiae | Ellis' shootingstar | Primulaceae | |
| Dodecatheon pulchellum | darkthroat shootingstar | Primulaceae | |
| Dodecatheon pulchellum ssp. pulchellum | darkthroat shootingstar | Primulaceae | |
| Dodonaea | dodonaea | Sapindaceae | |
| Dodonaea viscosa | Florida hopbush | Sapindaceae | |
| Draba | draba | Brassicaceae | |
| Draba albertina | slender draba | Brassicaceae | |
| Draba asprella | rough draba | Brassicaceae | |
| Draba asprella var. asprella | rough draba | Brassicaceae | |
| Draba asprella var. kaibabensis | Kaibab draba | Brassicaceae | |
| Draba asprella var. stelligera | rough draba | Brassicaceae | |
| Draba aurea | golden draba | Brassicaceae | |
| Draba brachycarpa | shortpod draba | Brassicaceae | |
| Draba crassifolia | snowbed draba | Brassicaceae | |
| Draba cuneifolia | wedgeleaf draba | Brassicaceae | |
| Draba cuneifolia var. cuneifolia | wedgeleaf draba | Brassicaceae | |
| Draba cuneifolia var. integrifolia | wedgeleaf draba | Brassicaceae | |
| Draba cuneifolia var. sonorae | Sonora draba | Brassicaceae | |
| Draba helleriana | Heller's draba | Brassicaceae | |
| Draba helleriana var. bifurcata | Heller's draba | Brassicaceae | |
| Draba helleriana var. blumeri | Blumer's draba | Brassicaceae | |
| Draba helleriana var. patens | Heller's draba | Brassicaceae | |
| Draba nemorosa | woodland draba | Brassicaceae | |
| Draba petrophila | Santa Rita Mountain draba | Brassicaceae | |
| Draba petrophila var. petrophila | Santa Rita Mountain draba | Brassicaceae | |
| Draba petrophila var. viridis | Santa Rita Mountain draba | Brassicaceae | |
| Draba platycarpa | broadpod draba | Brassicaceae | |
| Draba rectifructa | mountain draba | Brassicaceae | |
| Draba reptans | Carolina draba | Brassicaceae | |
| Draba spectabilis | showy draba | Brassicaceae | |
| Draba spectabilis var. spectabilis | showy draba | Brassicaceae | |
| Draba standleyi | Standley's draba | Brassicaceae | |
| Dracocephalum | dragonhead | Lamiaceae | |
| Dracocephalum parviflorum | American dragonhead | Lamiaceae | |
| Drymaria | drymary | Caryophyllaceae | |
| Drymaria effusa | pinewoods drymary | Caryophyllaceae | |
| Drymaria effusa var. depressa | pinewoods drymary | Caryophyllaceae | |
| Drymaria effusa var. effusa | pinewoods drymary | Caryophyllaceae | |
| Drymaria glandulosa | Fendler's drymary | Caryophyllaceae | |
| Drymaria leptophylla | canyon drymary | Caryophyllaceae | |
| Drymaria molluginea | slimleaf drymary | Caryophyllaceae | |
| Drymaria pachyphylla | thickleaf drymary | Caryophyllaceae | |
| Drymaria viscosa | sticky drymary | Caryophyllaceae | |
| Dryopetalon | dryopetalon | Brassicaceae | |
| Dryopetalon runcinatum | rockmustard | Brassicaceae | |
| Dryopteris | woodfern | Dryopteridaceae | |
| Dryopteris arguta | coastal woodfern | Dryopteridaceae | |
| Dryopteris cinnamomea | cinnamon woodfern | Dryopteridaceae | |
| Dryopteris filix-mas | male fern | Dryopteridaceae | |
| Dryopteris rossii | Ross' woodfern | Dryopteridaceae | |
| Dudleya | dudleya | Crassulaceae | |
| Dudleya collomiae | Gila County liveforever | Crassulaceae | |
| Dudleya pulverulenta | chalk dudleya | Crassulaceae | |
| Dudleya pulverulenta ssp. arizonica | chalk dudleya | Crassulaceae | |
| Duranta | duranta | Verbenaceae | |
| Duranta erecta | golden dewdrops | Verbenaceae | |
| Dyschoriste | snakeherb | Acanthaceae | |
| Dyschoriste schiedeana | Schied's snakeherb | Acanthaceae | |
| Dyschoriste schiedeana var. decumbens | spreading snakeherb | Acanthaceae | |
| Dyssodia | dyssodia | Asteraceae | |
| Dyssodia papposa | fetid marigold | Asteraceae | |
| E | |||
| Echeandia | echeandia | Liliaceae | |
| Echeandia flavescens | Torrey's craglily | Liliaceae | |
| Echinocactus | echinocactus | Cactaceae | |
| Echinocactus horizonthalonius | devilshead | Cactaceae | |
| Echinocactus horizonthalonius var. horizonthalonius | devilshead | Cactaceae | |
| Echinocactus horizonthalonius var. nicholii | Nichol's echinocactus | Cactaceae | |
| Echinocactus polycephalus | cottontop cactus | Cactaceae | |
| Echinocactus polycephalus var. polycephalus | cottontop cactus | Cactaceae | |
| Echinocactus polycephalus var. xeranthemoides | cottontop cactus | Cactaceae | |
| Echinocereus | hedgehog cactus | Cactaceae | |
| Echinocereus apachensis | Apache hedgehog cactus | Cactaceae | |
| Echinocereus bonkerae | pinkflower hedgehog cactus | Cactaceae | |
| Echinocereus boyce-thompsonii | Boyce Thompson hedgehog cactus | Cactaceae | |
| Echinocereus coccineus | scarlet hedgehog cactus | Cactaceae | |
| Echinocereus coccineus var. arizonicus | Arizona hedgehog cactus | Cactaceae | |
| Echinocereus coccineus var. coccineus | scarlet hedgehog cactus | Cactaceae | |
| Echinocereus dasyacanthus | spiny hedgehog cactus | Cactaceae | |
| Echinocereus engelmannii | Engelmann's hedgehog cactus | Cactaceae | |
| Echinocereus engelmannii var. acicularis | Engelmann's hedgehog cactus | Cactaceae | |
| Echinocereus engelmannii var. chrysocentrus | Engelmann's hedgehog cactus | Cactaceae | |
| Echinocereus engelmannii var. engelmannii | Engelmann's hedgehog cactus | Cactaceae | |
| Echinocereus engelmannii var. variegatus | Engelmann's hedgehog cactus | Cactaceae | |
| Echinocereus fasciculatus | pinkflower hedgehog cactus | Cactaceae | |
| Echinocereus fendleri | pinkflower hedgehog cactus | Cactaceae | |
| Echinocereus fendleri ssp. fendleri | pinkflower hedgehog cactus | Cactaceae | |
| Echinocereus fendleri ssp. rectispinus | pinkflower hedgehog cactus | Cactaceae | |
| Echinocereus ledingii | Leding's hedgehog cactus | Cactaceae | |
| Echinocereus mojavensis | Mojave kingcup cactus | Cactaceae | |
| Echinocereus nicholii | Nichol's hedgehog cactus | Cactaceae | |
| Echinocereus pectinatus | rainbow cactus | Cactaceae | |
| Echinocereus pectinatus var. pectinatus | rainbow cactus | Cactaceae | |
| Echinocereus polyacanthus | Mojave mound cactus | Cactaceae | |
| Echinocereus rigidissimus | rainbow hedgehog cactus | Cactaceae | |
| Echinocereus triglochidiatus | kingcup cactus | Cactaceae | |
| Echinocereus triglochidiatus var. triglochidiatus | kingcup cactus | Cactaceae | |
| Echinochloa | cockspur grass | Poaceae | |
| Echinochloa colona | jungle rice | Poaceae | |
| Echinochloa crus-galli | barnyardgrass | Poaceae | |
| Echinochloa crus-pavonis | gulf cockspur grass | Poaceae | |
| Echinochloa crus-pavonis var. macera | gulf cockspur grass | Poaceae | |
| Echinochloa muricata | rough barnyardgrass | Poaceae | |
| Echinochloa muricata var. microstachya | rough barnyardgrass | Poaceae | |
| Echinochloa oplismenoides | Chihuahuan cockspur | Poaceae | |
| Echinocystis | echinocystis | Cucurbitaceae | |
| Echinocystis lobata | wild cucumber | Cucurbitaceae | |
| Echinodorus | burhead | Alismataceae | |
| Echinodorus berteroi | upright burhead | Alismataceae | |
| Echinomastus | Cactaceae | ||
| Echinomastus erectocentrus | redspine fishhook cactus | Cactaceae | |
| Echinomastus intertextus | white fishhook cactus | Cactaceae | |
| Echinomastus johnsonii | Johnson's fishhook cactus | Cactaceae | |
| Echinopepon | balsam apple | Cucurbitaceae | |
| Echinopepon wrightii | wild balsam apple | Cucurbitaceae | |
| Eclipta | eclipta | Asteraceae | |
| Eclipta prostrata | false daisy | Asteraceae | |
| Egeria | egeria | Hydrocharitaceae | |
| Egeria densa | Brazilian waterweed | Hydrocharitaceae | |
| Eichhornia | water hyacinth | Pontederiaceae | |
| Eichhornia crassipes | common water hyacinth | Pontederiaceae | |
| Elaeagnus | oleaster | Elaeagnaceae | |
| Elaeagnus angustifolia | Russian olive | Elaeagnaceae | |
| Elatine | waterwort | Elatinaceae | |
| Elatine brachysperma | shortseed waterwort | Elatinaceae | |
| Elatine californica | California waterwort | Elatinaceae | |
| Elatine chilensis | Chilean waterwort | Elatinaceae | |
| Elatine rubella | southwestern waterwort | Elatinaceae | |
| Eleocharis | spikerush | Cyperaceae | |
| Eleocharis acicularis | needle spikerush | Cyperaceae | |
| Eleocharis acicularis var. acicularis | needle spikerush | Cyperaceae | |
| Eleocharis acicularis var. porcata | Cyperaceae | ||
| Eleocharis bella | beautiful spikerush | Cyperaceae | |
| Eleocharis bolanderi | Bolander's spikerush | Cyperaceae | |
| Eleocharis cancellata | Arizona spikerush | Cyperaceae | |
| Eleocharis engelmannii | Engelmann's spikerush | Cyperaceae | |
| Eleocharis flavescens | yellow spikerush | Cyperaceae | |
| Eleocharis flavescens var. thermalis | yellow spikerush | Cyperaceae | |
| Eleocharis geniculata | Canada spikesedge | Cyperaceae | |
| Eleocharis macrostachya | pale spikerush | Cyperaceae | |
| Eleocharis montana | mountain spikerush | Cyperaceae | |
| Eleocharis montevidensis | sand spikerush | Cyperaceae | |
| Eleocharis palustris | common spikerush | Cyperaceae | |
| Eleocharis palustris var. palustris | common spikerush | Cyperaceae | |
| Eleocharis parishii | Parish's spikerush | Cyperaceae | |
| Eleocharis parvula | dwarf spikerush | Cyperaceae | |
| Eleocharis quinqueflora | fewflower spikerush | Cyperaceae | |
| Eleocharis radicans | rooted spikerush | Cyperaceae | |
| Eleocharis rostellata | beaked spikerush | Cyperaceae | |
| Eleusine | goosegrass | Poaceae | |
| Eleusine indica | Indian goosegrass | Poaceae | |
| Elionurus | balsamscale grass | Poaceae | |
| Elionurus barbiculmis | woolyspike balsamscale | Poaceae | |
| Elodea | waterweed | Hydrocharitaceae | |
| Elodea bifoliata | twoleaf waterweed | Hydrocharitaceae | |
| Elodea canadensis | Canadian waterweed | Hydrocharitaceae | |
| Elymus | wildrye | Poaceae | |
| Elymus arizonicus | Arizona wheatgrass | Poaceae | |
| Elymus canadensis | Canada wildrye | Poaceae | |
| Elymus elymoides | squirreltail | Poaceae | |
| Elymus elymoides ssp. brevifolius | squirreltail | Poaceae | |
| Elymus elymoides ssp. elymoides | squirreltail | Poaceae | |
| Elymus glaucus | blue wildrye | Poaceae | |
| Elymus glaucus ssp. glaucus | blue wildrye | Poaceae | |
| Elymus interruptus | Texas wildrye | Poaceae | |
| Elymus lanceolatus | thickspike wheatgrass | Poaceae | |
| Elymus lanceolatus ssp. lanceolatus | thickspike wheatgrass | Poaceae | |
| Elymus multisetus | big squirreltail | Poaceae | |
| Elymus pinaloensis | Poaceae | ||
| Elymus pseudorepens | Poaceae | ||
| Elymus repens | quackgrass | Poaceae | |
| Elymus saundersii | Poaceae | ||
| Elymus scribneri | spreading wheatgrass | Poaceae | |
| Elymus trachycaulus | slender wheatgrass | Poaceae | |
| Elymus trachycaulus ssp. subsecundus | slender wheatgrass | Poaceae | |
| Elymus trachycaulus ssp. trachycaulus | slender wheatgrass | Poaceae | |
| Elymus virginicus | Virginia wildrye | Poaceae | |
| Elymus virginicus var. virginicus | Virginia wildrye | Poaceae | |
| Elytraria | scalystem | Acanthaceae | |
| Elytraria imbricata | purple scalystem | Acanthaceae | |
| Emmenanthe | whisperingbells | Hydrophyllaceae | |
| Emmenanthe penduliflora | whisperingbells | Hydrophyllaceae | |
| Emmenanthe penduliflora var. penduliflora | whisperingbells | Hydrophyllaceae | |
| Encelia | brittlebush | Asteraceae | |
| Encelia farinosa | brittlebush | Asteraceae | |
| Encelia frutescens | button brittlebush | Asteraceae | |
| Encelia resinifera | sticky brittlebush | Asteraceae | |
| Encelia resinifera ssp. resinifera | button brittlebush | Asteraceae | |
| Encelia resinifera ssp. tenuifolia | Asteraceae | ||
| Encelia virginensis | Virgin River brittlebush | Asteraceae | |
| Enceliopsis | sunray | Asteraceae | |
| Enceliopsis argophylla | silverleaf sunray | Asteraceae | |
| Enceliopsis nudicaulis | nakedstem sunray | Asteraceae | |
| Enceliopsis nudicaulis var. nudicaulis | nakedstem sunray | Asteraceae | |
| Engelmannia | Engelmann's daisy | Asteraceae | |
| Engelmannia peristenia | Engelmann's daisy | Asteraceae | |
| Enneapogon | feather pappusgrass | Poaceae | |
| Enneapogon cenchroides | soft feather pappusgrass | Poaceae | |
| Enneapogon desvauxii | nineawn pappusgrass | Poaceae | |
| Enteropogon | unbrellagrass | Poaceae | |
| Enteropogon chlorideus | buryseed umbrellagrass | Poaceae | |
| Ephedra | jointfir | Ephedraceae | |
| Ephedra arenicola | Ephedraceae | ||
| Ephedra aspera | rough jointfir | Ephedraceae | |
| Ephedra californica | California jointfir | Ephedraceae | |
| Ephedra cutleri | Cutler's jointfir | Ephedraceae | |
| Ephedra fasciculata | Arizona jointfir | Ephedraceae | |
| Ephedra funerea | Death Valley jointfir | Ephedraceae | |
| Ephedra nevadensis | Nevada jointfir | Ephedraceae | |
| Ephedra torreyana | Torrey's jointfir | Ephedraceae | |
| Ephedra torreyana var. torreyana | Torrey's jointfir | Ephedraceae | |
| Ephedra trifurca | longleaf jointfir | Ephedraceae | |
| Ephedra viridis | mormon tea | Ephedraceae | |
| Epilobium | willowherb | Onagraceae | |
| Epilobium brachycarpum | tall annual willowherb | Onagraceae | |
| Epilobium canum | hummingbird trumpet | Onagraceae | |
| Epilobium canum ssp. garrettii | Garrett's firechalice | Onagraceae | |
| Epilobium canum ssp. latifolium | hummingbird trumpet | Onagraceae | |
| Epilobium ciliatum | fringed willowherb | Onagraceae | |
| Epilobium ciliatum ssp. ciliatum | fringed willowherb | Onagraceae | |
| Epilobium ciliatum ssp. glandulosum | fringed willowherb | Onagraceae | |
| Epilobium densiflorum | denseflower willowherb | Onagraceae | |
| Epilobium foliosum | leafy willowherb | Onagraceae | |
| Epilobium halleanum | glandular willowherb | Onagraceae | |
| Epilobium hornemannii | Hornemann's willowherb | Onagraceae | |
| Epilobium hornemannii ssp. hornemannii | Hornemann's willowherb | Onagraceae | |
| Epilobium lactiflorum | milkflower willowherb | Onagraceae | |
| Epilobium minutum | chaparral willowherb | Onagraceae | |
| Epilobium oregonense | Oregon willowherb | Onagraceae | |
| Epilobium pygmaeum | smooth spike-primrose | Onagraceae | |
| Epilobium saximontanum | Rocky Mountain willowherb | Onagraceae | |
| Epipactis | helleborine | Orchidaceae | |
| Epipactis gigantea | stream orchid | Orchidaceae | |
| Epithelantha | pingpong-ball cactus | Cactaceae | |
| Epithelantha micromeris | pingpong-ball cactus | Cactaceae | |
| Epixiphium | epixiphium | Scrophulariaceae | |
| Epixiphium wislizeni | balloonbush | Scrophulariaceae | |
| Equisetum | horsetail | Equisetaceae | |
| Equisetum arvense | field horsetail | Equisetaceae | |
| Equisetum ferrissii | Equisetaceae | ||
| Equisetum hyemale | scouringrush horsetail | Equisetaceae | |
| Equisetum hyemale var. affine | scouringrush horsetail | Equisetaceae | |
| Equisetum laevigatum | smooth horsetail | Equisetaceae | |
| Eragrostis | lovegrass | Poaceae | |
| Eragrostis barrelieri | Mediterranean lovegrass | Poaceae | |
| Eragrostis cilianensis | stinkgrass | Poaceae | |
| Eragrostis curvula | weeping lovegrass | Poaceae | |
| Eragrostis echinochloidea | African lovegrass | Poaceae | |
| Eragrostis intermedia | plains lovegrass | Poaceae | |
| Eragrostis lehmanniana | Lehmann lovegrass | Poaceae | |
| Eragrostis lutescens | sixweeks lovegrass | Poaceae | |
| Eragrostis mexicana | Mexican lovegrass | Poaceae | |
| Eragrostis mexicana ssp. mexicana | Mexican lovegrass | Poaceae | |
| Eragrostis mexicana ssp. virescens | Mexican lovegrass | Poaceae | |
| Eragrostis obtusiflora | alkali lovegrass | Poaceae | |
| Eragrostis pectinacea | tufted lovegrass | Poaceae | |
| Eragrostis pectinacea var. miserrima | desert lovegrass | Poaceae | |
| Eragrostis pectinacea var. pectinacea | tufted lovegrass | Poaceae | |
| Eragrostis pilosa | Indian lovegrass | Poaceae | |
| Eragrostis spectabilis | purple lovegrass | Poaceae | |
| Eragrostis superba | Wilman lovegrass | Poaceae | |
| Eremalche | mallow | Malvaceae | |
| Eremalche exilis | white mallow | Malvaceae | |
| Eremalche rotundifolia | desert fivespot | Malvaceae | |
| Eremocrinum | eremocrinum | Liliaceae | |
| Eremocrinum albomarginatum | lonely lily | Liliaceae | |
| Eremopyrum | false wheatgrass | Poaceae | |
| Eremopyrum triticeum | annual wheatgrass | Poaceae | |
| Eriastrum | woollystar | Polemoniaceae | |
| Eriastrum diffusum | miniature woollystar | Polemoniaceae | |
| Eriastrum eremicum | desert woollystar | Polemoniaceae | |
| Eriastrum eremicum ssp. eremicum | desert woollystar | Polemoniaceae | |
| Eriastrum eremicum ssp. yageri | Yager's woollystar | Polemoniaceae | |
| Ericameria | goldenbush | Asteraceae | |
| Ericameria cervina | deer goldenbush | Asteraceae | |
| Ericameria cuneata | cliff goldenbush | Asteraceae | |
| Ericameria cuneata var. spathulata | cliff goldenbush | Asteraceae | |
| Ericameria laricifolia | turpentine bush | Asteraceae | |
| Ericameria linearifolia | narrowleaf goldenbush | Asteraceae | |
| Ericameria nauseosa | rubber rabbitbrush | Asteraceae | |
| Ericameria nauseosa ssp. consimilis | rubber rabbitbrush | Asteraceae | |
| Ericameria nauseosa ssp. consimilis var. arenaria | rubber rabbitbrush | Asteraceae | |
| Ericameria nauseosa ssp. consimilis var. juncea | rubber rabbitbrush | Asteraceae | |
| Ericameria nauseosa ssp. consimilis var. leiosperma | rubber rabbitbrush | Asteraceae | |
| Ericameria nauseosa ssp. consimilis var. nitida | rubber rabbitbrush | Asteraceae | |
| Ericameria nauseosa ssp. consimilis var. oreophila | rubber rabbitbrush | Asteraceae | |
| Ericameria nauseosa ssp. consimilis var. turbinata | rubber rabbitbrush | Asteraceae | |
| Ericameria nauseosa ssp. nauseosa | rubber rabbitbrush | Asteraceae | |
| Ericameria nauseosa ssp. nauseosa var. bigelovii | rubber rabbitbrush | Asteraceae | |
| Ericameria nauseosa ssp. nauseosa var. glabrata | rubber rabbitbrush | Asteraceae | |
| Ericameria nauseosa ssp. nauseosa var. hololeuca | rubber rabbitbrush | Asteraceae | |
| Ericameria nauseosa ssp. nauseosa var. latisquamea | rubber rabbitbrush | Asteraceae | |
| Ericameria paniculata | Mojave rabbitbrush | Asteraceae | |
| Ericameria parryi | Parry's rabbitbrush | Asteraceae | |
| Ericameria parryi var. attenuata | Parry's rabbitbrush | Asteraceae | |
| Ericameria parryi var. howardii | Parry's rabbitbrush | Asteraceae | |
| Ericameria parryi var. nevadensis | Parry's rabbitbrush | Asteraceae | |
| Ericameria teretifolia | green rabbitbrush | Asteraceae | |
| Ericameria watsonii | Watson's goldenbush | Asteraceae | |
| Erigeron | fleabane | Asteraceae | |
| Erigeron anchana | Sierra Ancha fleabane | Asteraceae | |
| Erigeron aphanactis | rayless shaggy fleabane | Asteraceae | |
| Erigeron aphanactis var. aphanactis | rayless shaggy fleabane | Asteraceae | |
| Erigeron arisolius | arid throne fleabane | Asteraceae | |
| Erigeron arizonicus | Arizona fleabane | Asteraceae | |
| Erigeron bellidiastrum | western daisy fleabane | Asteraceae | |
| Erigeron bellidiastrum var. bellidiastrum | western daisy fleabane | Asteraceae | |
| Erigeron caespitosus | tufted fleabane | Asteraceae | |
| Erigeron canus | hoary fleabane | Asteraceae | |
| Erigeron colomexicanus | running fleabane | Asteraceae | |
| Erigeron compactus | cushion daisy | Asteraceae | |
| Erigeron compositus | cutleaf daisy | Asteraceae | |
| Erigeron concinnus | Navajo fleabane | Asteraceae | |
| Erigeron concinnus var. concinnus | Navajo fleabane | Asteraceae | |
| Erigeron concinnus var. condensatus | Navajo fleabane | Asteraceae | |
| Erigeron concinnus var. subglaber | Navajo fleabane | Asteraceae | |
| Erigeron consimilis | foothill fleabane | Asteraceae | |
| Erigeron divergens | spreading fleabane | Asteraceae | |
| Erigeron eatonii | Eaton's fleabane | Asteraceae | |
| Erigeron eatonii var. eatonii | Eaton's fleabane | Asteraceae | |
| Erigeron eximius | sprucefir fleabane | Asteraceae | |
| Erigeron flagellaris | trailing fleabane | Asteraceae | |
| Erigeron formosissimus | beautiful fleabane | Asteraceae | |
| Erigeron heliographis | Heliograph Peak fleabane | Asteraceae | |
| Erigeron kuschei | Chiricahua fleabane | Asteraceae | |
| Erigeron lemmonii | Lemmon's fleabane | Asteraceae | |
| Erigeron lobatus | lobed fleabane | Asteraceae | |
| Erigeron lonchophyllus | shortray fleabane | Asteraceae | |
| Erigeron modestus | plains fleabane | Asteraceae | |
| Erigeron neomexicanus | New Mexico fleabane | Asteraceae | |
| Erigeron oreophilus | chaparral fleabane | Asteraceae | |
| Erigeron oxyphyllus | wand fleabane | Asteraceae | |
| Erigeron piscaticus | Fish Creek fleabane | Asteraceae | |
| Erigeron pringlei | Pringle's fleabane | Asteraceae | |
| Erigeron pumilus | shaggy fleabane | Asteraceae | |
| Erigeron pumilus ssp. pumilus | shaggy fleabane | Asteraceae | |
| Erigeron rhizomatus | rhizome fleabane | Asteraceae | |
| Erigeron saxatilis | rock fleabane | Asteraceae | |
| Erigeron sceptrifer | scepterbearing fleabane | Asteraceae | |
| Erigeron scopulinus | Winn Falls fleabane | Asteraceae | |
| Erigeron simplex | onestem fleabane | Asteraceae | |
| Erigeron sivinskii | Sivinsk's erigeron | Asteraceae | |
| Erigeron speciosus | aspen fleabane | Asteraceae | |
| Erigeron speciosus var. macranthus | aspen fleabane | Asteraceae | |
| Erigeron tener | slender fleabane | Asteraceae | |
| Erigeron ursinus | Bear River fleabane | Asteraceae | |
| Erigeron utahensis | Utah fleabane | Asteraceae | |
| Erigeron utahensis var. sparsifolius | Utah fleabane | Asteraceae | |
| Erigeron utahensis var. utahensis | Utah fleabane | Asteraceae | |
| Erigeron velutipes | Chihuahuan fleabane | Asteraceae | |
| Erigeron versicolor | changing fleabane | Asteraceae | |
| Erigeron vreelandii | Vreeland's erigeron | Asteraceae | |
| Eriochloa | cupgrass | Poaceae | |
| Eriochloa acuminata | tapertip cupgrass | Poaceae | |
| Eriochloa acuminata var. acuminata | tapertip cupgrass | Poaceae | |
| Eriochloa acuminata var. minor | tapertip cupgrass | Poaceae | |
| Eriochloa aristata | bearded cupgrass | Poaceae | |
| Eriochloa contracta | prairie cupgrass | Poaceae | |
| Eriochloa fatmensis | tropical cupgrass | Poaceae | |
| Eriochloa lemmonii | canyon cupgrass | Poaceae | |
| Eriodictyon | yerba santa | Hydrophyllaceae | |
| Eriodictyon angustifolium | narrowleaf yerba santa | Hydrophyllaceae | |
| Eriogonum | buckwheat | Polygonaceae | |
| Eriogonum abertianum | Abert's buckwheat | Polygonaceae | |
| Eriogonum alatum | winged buckwheat | Polygonaceae | |
| Eriogonum alatum var. alatum | winged buckwheat | Polygonaceae | |
| Eriogonum alatum var. mogollense | winged buckwheat | Polygonaceae | |
| Eriogonum arizonicum | Arizona buckwheat | Polygonaceae | |
| Eriogonum brachypodum | Parry's buckwheat | Polygonaceae | |
| Eriogonum caespitosum | matted buckwheat | Polygonaceae | |
| Eriogonum capillare | San Carlos buckwheat | Polygonaceae | |
| Eriogonum cernuum | nodding buckwheat | Polygonaceae | |
| Eriogonum cernuum var. cernuum | nodding buckwheat | Polygonaceae | |
| Eriogonum corymbosum | crispleaf buckwheat | Polygonaceae | |
| Eriogonum corymbosum var. corymbosum | crispleaf buckwheat | Polygonaceae | |
| Eriogonum corymbosum var. glutinosum | crispleaf buckwheat | Polygonaceae | |
| Eriogonum corymbosum var. orbiculatum | crispleaf buckwheat | Polygonaceae | |
| Eriogonum corymbosum var. velutinum | crispleaf buckwheat | Polygonaceae | |
| Eriogonum darrovii | Darrow's buckwheat | Polygonaceae | |
| Eriogonum davidsonii | Davidson's buckwheat | Polygonaceae | |
| Eriogonum deflexum | flatcrown buckwheat | Polygonaceae | |
| Eriogonum deflexum var. deflexum | flatcrown buckwheat | Polygonaceae | |
| Eriogonum deserticola | Colorado Desert buckwheat | Polygonaceae | |
| Eriogonum divaricatum | divergent buckwheat | Polygonaceae | |
| Eriogonum ericifolium | Yavapai County buckwheat | Polygonaceae | |
| Eriogonum ericifolium var. ericifolium | Yavapai County buckwheat | Polygonaceae | |
| Eriogonum fasciculatum | Eastern Mojave buckwheat | Polygonaceae | |
| Eriogonum fasciculatum var. foliolosum | Eastern Mojave buckwheat | Polygonaceae | |
| Eriogonum fasciculatum var. polifolium | Eastern Mojave buckwheat | Polygonaceae | |
| Eriogonum gordonii | Gordon's buckwheat | Polygonaceae | |
| Eriogonum heermannii | Heermann's buckwheat | Polygonaceae | |
| Eriogonum heermannii var. apachense | Apache buckwheat | Polygonaceae | |
| Eriogonum heermannii var. argense | Heermann's buckwheat | Polygonaceae | |
| Eriogonum heermannii var. floccosum | Clark Mountain buckwheat | Polygonaceae | |
| Eriogonum heermannii var. subracemosum | Heermann's buckwheat | Polygonaceae | |
| Eriogonum heermannii var. subspinosum | Heermann's buckwheat | Polygonaceae | |
| Eriogonum heermannii var. sulcatum | Heermann's buckwheat | Polygonaceae | |
| Eriogonum hieraciifolium | hawkweed buckwheat | Polygonaceae | |
| Eriogonum hookeri | Hooker's buckwheat | Polygonaceae | |
| Eriogonum inflatum | desert trumpet | Polygonaceae | |
| Eriogonum inflatum var. deflatum | desert trumpet | Polygonaceae | |
| Eriogonum inflatum var. inflatum | desert trumpet | Polygonaceae | |
| Eriogonum insigne | ladder buckwheat | Polygonaceae | |
| Eriogonum jamesii | James' buckwheat | Polygonaceae | |
| Eriogonum jamesii var. flavescens | James' buckwheat | Polygonaceae | |
| Eriogonum jamesii var. jamesii | James' buckwheat | Polygonaceae | |
| Eriogonum jamesii var. undulatum | James' buckwheat | Polygonaceae | |
| Eriogonum jonesii | Jones' buckwheat | Polygonaceae | |
| Eriogonum lachnogynum | woollycup buckwheat | Polygonaceae | |
| Eriogonum leptocladon | sand buckwheat | Polygonaceae | |
| Eriogonum leptocladon var. leptocladon | sand buckwheat | Polygonaceae | |
| Eriogonum leptocladon var. papiliunculi | sand buckwheat | Polygonaceae | |
| Eriogonum leptocladon var. ramosissimum | sand buckwheat | Polygonaceae | |
| Eriogonum leptophyllum | slenderleaf buckwheat | Polygonaceae | |
| Eriogonum maculatum | spotted buckwheat | Polygonaceae | |
| Eriogonum microthecum | slender buckwheat | Polygonaceae | |
| Eriogonum microthecum var. laxiflorum | slender buckwheat | Polygonaceae | |
| Eriogonum microthecum var. simpsonii | Simpson's buckwheat | Polygonaceae | |
| Eriogonum mortonianum | Fredonia buckwheat | Polygonaceae | |
| Eriogonum nidularium | birdnest buckwheat | Polygonaceae | |
| Eriogonum nummulare | money buckwheat | Polygonaceae | |
| Eriogonum ovalifolium | cushion buckwheat | Polygonaceae | |
| Eriogonum ovalifolium var. purpureum | cushion buckwheat | Polygonaceae | |
| Eriogonum palmerianum | Palmer's buckwheat | Polygonaceae | |
| Eriogonum parishii | mountainmist | Polygonaceae | |
| Eriogonum pharnaceoides | wirestem buckwheat | Polygonaceae | |
| Eriogonum pharnaceoides var. cervinum | wirestem buckwheat | Polygonaceae | |
| Eriogonum pharnaceoides var. pharnaceoides | wirestem buckwheat | Polygonaceae | |
| Eriogonum plumatella | yucca buckwheat | Polygonaceae | |
| Eriogonum polycladon | sorrel buckwheat | Polygonaceae | |
| Eriogonum pulchrum | Yavapai County buckwheat | Polygonaceae | |
| Eriogonum pusillum | yellowturbans | Polygonaceae | |
| Eriogonum racemosum | redroot buckwheat | Polygonaceae | |
| Eriogonum reniforme | kidneyleaf buckwheat | Polygonaceae | |
| Eriogonum ripleyi | Fraziers Well buckwheat | Polygonaceae | |
| Eriogonum rotundifolium | roundleaf buckwheat | Polygonaceae | |
| Eriogonum shockleyi | Shockley's buckwheat | Polygonaceae | |
| Eriogonum subreniforme | kidneyshape buckwheat | Polygonaceae | |
| Eriogonum thomasii | Thomas' buckwheat | Polygonaceae | |
| Eriogonum thompsoniae | Thompson's buckwheat | Polygonaceae | |
| Eriogonum thompsoniae var. albiflorum | Thompson's buckwheat | Polygonaceae | |
| Eriogonum thompsoniae var. atwoodii | Atwood's buckwheat | Polygonaceae | |
| Eriogonum thompsoniae var. thompsoniae | Thompson's buckwheat | Polygonaceae | |
| Eriogonum thurberi | Thurber's buckwheat | Polygonaceae | |
| Eriogonum trichopes | little deserttrumpet | Polygonaceae | |
| Eriogonum trichopes var. trichopes | little deserttrumpet | Polygonaceae | |
| Eriogonum umbellatum | sulphur-flower buckwheat | Polygonaceae | |
| Eriogonum umbellatum var. cognatum | sulphur-flower buckwheat | Polygonaceae | |
| Eriogonum umbellatum var. nevadense | sulphur-flower buckwheat | Polygonaceae | |
| Eriogonum umbellatum var. subaridum | sulphur-flower buckwheat | Polygonaceae | |
| Eriogonum viridulum | clay hill buckwheat | Polygonaceae | |
| Eriogonum wetherillii | Wetherill's buckwheat | Polygonaceae | |
| Eriogonum wrightii | bastardsage | Polygonaceae | |
| Eriogonum wrightii var. nodosum | bastardsage | Polygonaceae | |
| Eriogonum wrightii var. pringlei | Pringle's bastardsage | Polygonaceae | |
| Eriogonum wrightii var. wrightii | bastardsage | Polygonaceae | |
| Eriogonum zionis | Zion buckwheat | Polygonaceae | |
| Eriogonum zionis var. coccineum | Zion buckwheat | Polygonaceae | |
| Eriogonum zionis var. zionis | Zion buckwheat | Polygonaceae | |
| Erioneuron | woollygrass | Poaceae | |
| Erioneuron avenaceum | shortleaf woollygrass | Poaceae | |
| Erioneuron pilosum | hairy woollygrass | Poaceae | |
| Eriophyllum | woolly sunflower | Asteraceae | |
| Eriophyllum confertiflorum | golden-yarrow | Asteraceae | |
| Eriophyllum confertiflorum var. confertiflorum | golden-yarrow | Asteraceae | |
| Eriophyllum multicaule | manystem woolly sunflower | Asteraceae | |
| Eriophyllum pringlei | Pringle's woolly sunflower | Asteraceae | |
| Erodium | stork's bill | Geraniaceae | |
| Erodium cicutarium | redstem stork's bill | Geraniaceae | |
| Erodium cicutarium ssp. cicutarium | redstem stork's bill | Geraniaceae | |
| Erodium moschatum | musky stork's bill | Geraniaceae | |
| Erodium moschatum var. moschatum | musky stork's bill | Geraniaceae | |
| Erodium texanum | Texas stork's bill | Geraniaceae | |
| Errazurizia | dunebroom | Fabaceae | |
| Errazurizia rotundata | roundleaf dunebroom | Fabaceae | |
| Eruca | rocketsalad | Brassicaceae | |
| Eruca vesicaria | rocketsalad | Brassicaceae | |
| Eruca vesicaria ssp. sativa | rocketsalad | Brassicaceae | |
| Eryngium | eryngo | Apiaceae | |
| Eryngium heterophyllum | Wright's eryngo | Apiaceae | |
| Eryngium lemmonii | Chiricahua Mountain eryngo | Apiaceae | |
| Eryngium nasturtiifolium | hierba del sapo | Apiaceae | |
| Eryngium phyteumae | Huachuca Mountain eryngo | Apiaceae | |
| Eryngium sparganophyllum | Arizona eryngo | Apiaceae | |
| Erysimum | wallflower | Brassicaceae | |
| Erysimum capitatum | sanddune wallflower | Brassicaceae | |
| Erysimum capitatum var. capitatum | sanddune wallflower | Brassicaceae | |
| Erysimum capitatum var. purshii | Pursh's wallflower | Brassicaceae | |
| Erysimum cheiranthoides | wormseed wallflower | Brassicaceae | |
| Erysimum inconspicuum | shy wallflower | Brassicaceae | |
| Erysimum inconspicuum var. inconspicuum | shy wallflower | Brassicaceae | |
| Erysimum repandum | spreading wallflower | Brassicaceae | |
| Erythrina | erythrina | Fabaceae | |
| Erythrina flabelliformis | coralbean | Fabaceae | |
| Eschscholzia | California poppy | Papaveraceae | |
| Eschscholzia californica | California poppy | Papaveraceae | |
| Eschscholzia californica ssp. californica | California poppy | Papaveraceae | |
| Eschscholzia californica ssp. mexicana | California poppy | Papaveraceae | |
| Eschscholzia glyptosperma | desert poppy | Papaveraceae | |
| Eschscholzia minutiflora | pygmy poppy | Papaveraceae | |
| Eschscholzia minutiflora ssp. minutiflora | pygmy poppy | Papaveraceae | |
| Escobaria | foxtail cactus | Cactaceae | |
| Escobaria alversonii | cushion foxtail cactus | Cactaceae | |
| Escobaria missouriensis | Missouri foxtail cactus | Cactaceae | |
| Escobaria orcuttii | Orcutt's foxtail cactus | Cactaceae | |
| Escobaria orcuttii var. orcuttii | Orcutt's foxtail cactus | Cactaceae | |
| Escobaria robbinsiorum | Cochise foxtail cactus | Cactaceae | |
| Escobaria tuberculosa | whitecolumn foxtail cactus | Cactaceae | |
| Escobaria vivipara | spinystar | Cactaceae | |
| Escobaria vivipara var. arizonica | Arizona spinystar | Cactaceae | |
| Escobaria vivipara var. bisbeeana | Bisbee spinystar | Cactaceae | |
| Escobaria vivipara var. buoflama | spinystar | Cactaceae | |
| Escobaria vivipara var. deserti | desert spinystar | Cactaceae | |
| Escobaria vivipara var. kaibabensis | Kaibab spinystar | Cactaceae | |
| Escobaria vivipara var. rosea | spinystar | Cactaceae | |
| Escobaria vivipara var. vivipara | spinystar | Cactaceae | |
| Eucnide | stingbush | Loasaceae | |
| Eucnide rupestris | rock nettle | Loasaceae | |
| Eucnide urens | desert stingbush | Loasaceae | |
| Eucrypta | hideseed | Hydrophyllaceae | |
| Eucrypta chrysanthemifolia | spotted hideseed | Hydrophyllaceae | |
| Eucrypta chrysanthemifolia var. bipinnatifida | spotted hideseed | Hydrophyllaceae | |
| Eucrypta micrantha | dainty desert hideseed | Hydrophyllaceae | |
| Eupatoriadelphus | Asteraceae | ||
| Eupatoriadelphus maculatus | spotted trumpetweed | Asteraceae | |
| Eupatoriadelphus maculatus var. bruneri | spotted joe pye weed | Asteraceae | |
| Euphorbia | spurge | Euphorbiaceae | |
| Euphorbia aaron-rossii | Marble Canyon spurge | Euphorbiaceae | |
| Euphorbia bilobata | blackseed spurge | Euphorbiaceae | |
| Euphorbia brachycera | horned spurge | Euphorbiaceae | |
| Euphorbia chamaesula | mountain spurge | Euphorbiaceae | |
| Euphorbia crenulata | Chinese caps | Euphorbiaceae | |
| Euphorbia cuphosperma | hairy-fruit spurge | Euphorbiaceae | |
| Euphorbia cyathophora | fire on the mountain | Euphorbiaceae | |
| Euphorbia davidii | David's spurge | Euphorbiaceae | |
| Euphorbia dentata | toothed spurge | Euphorbiaceae | |
| Euphorbia dentata var. dentata | toothed spurge | Euphorbiaceae | |
| Euphorbia eriantha | beetle spurge | Euphorbiaceae | |
| Euphorbia esula | leafy spurge | Euphorbiaceae | |
| Euphorbia esula var. esula | leafy spurge | Euphorbiaceae | |
| Euphorbia exstipulata | squareseed spurge | Euphorbiaceae | |
| Euphorbia heterophylla | Mexican fireplant | Euphorbiaceae | |
| Euphorbia lathyris | moleplant | Euphorbiaceae | |
| Euphorbia macropus | Huachuca Mountain spurge | Euphorbiaceae | |
| Euphorbia marginata | snow on the mountain | Euphorbiaceae | |
| Euphorbia palmeri | woodland spurge | Euphorbiaceae | |
| Euphorbia palmeri var. palmeri | woodland spurge | Euphorbiaceae | |
| Euphorbia palmeri var. subpubens | woodland spurge | Euphorbiaceae | |
| Euphorbia peplus | petty spurge | Euphorbiaceae | |
| Euphorbia radians | sun spurge | Euphorbiaceae | |
| Euphorbia schizoloba | Mojave spurge | Euphorbiaceae | |
| Euphorbia spathulata | warty spurge | Euphorbiaceae | |
| Eurybia | aster | Asteraceae | |
| Eurybia glauca | gray aster | Asteraceae | |
| Eurybia pulchra | beautiful aster | Asteraceae | |
| Euryops | euryops | Asteraceae | |
| Euryops multifidus | hawk's eye | Asteraceae | |
| Eustoma | prairie gentian | Gentianaceae | |
| Eustoma exaltatum | catchfly prairie gentian | Gentianaceae | |
| Eustoma exaltatum ssp. exaltatum | catchfly prairie gentian | Gentianaceae | |
| Euthamia | goldentop | Asteraceae | |
| Euthamia occidentalis | western goldentop | Asteraceae | |
| Evax | pygmy cudweed | Asteraceae | |
| Evax verna | spring pygmycudweed | Asteraceae | |
| Evax verna var. verna | spring pygmycudweed | Asteraceae | |
| Evolvulus | dwarf morning-glory | Convolvulaceae | |
| Evolvulus alsinoides | slender dwarf morning-glory | Convolvulaceae | |
| Evolvulus alsinoides var. angustifolius | slender dwarf morning-glory | Convolvulaceae | |
| Evolvulus arizonicus | wild dwarf morning-glory | Convolvulaceae | |
| Evolvulus nuttallianus | shaggy dwarf morning-glory | Convolvulaceae | |
| Evolvulus sericeus | silver dwarf morning-glory | Convolvulaceae | |
| Evolvulus sericeus var. sericeus | silver dwarf morning-glory | Convolvulaceae | |
| Eysenhardtia | kidneywood | Fabaceae | |
| Eysenhardtia orthocarpa | Tahitian kidneywood | Fabaceae | |
| F | |||
| Fagonia | fagonbush | Zygophyllaceae | |
| Fagonia laevis | California fagonbush | Zygophyllaceae | |
| Fagonia pachyacantha | sticky fagonbush | Zygophyllaceae | |
| Fagopyrum | buckwheat | Polygonaceae | |
| Fagopyrum esculentum | buckwheat | Polygonaceae | |
| Fallugia | Apache plume | Rosaceae | |
| Fallugia paradoxa | Apache plume | Rosaceae | |
| Fendlera | fendlerbush | Hydrangeaceae | |
| Fendlera rupicola | cliff fendlerbush | Hydrangeaceae | |
| Fendlera wrightii | Wright's fendlerbush | Hydrangeaceae | |
| Fendlerella | fendlerbush | Hydrangeaceae | |
| Fendlerella utahensis | Utah fendlerbush | Hydrangeaceae | |
| Fendlerella utahensis var. cymosa | Utah fendlerbush | Hydrangeaceae | |
| Fendlerella utahensis var. utahensis | Utah fendlerbush | Hydrangeaceae | |
| Ferocactus | barrel cactus | Cactaceae | |
| Ferocactus cylindraceus | California barrel cactus | Cactaceae | |
| Ferocactus cylindraceus var. cylindraceus | California barrel cactus | Cactaceae | |
| Ferocactus cylindraceus var. lecontei | Leconte's barrel cactus | Cactaceae | |
| Ferocactus eastwoodiae | California barrel cactus | Cactaceae | |
| Ferocactus emoryi | Emory's barrel cactus | Cactaceae | |
| Ferocactus wislizeni | candy barrelcactus | Cactaceae | |
| Festuca | fescue | Poaceae | |
| Festuca arizonica | Arizona fescue | Poaceae | |
| Festuca brachyphylla | alpine fescue | Poaceae | |
| Festuca brachyphylla ssp. coloradensis | Colorado fescue | Poaceae | |
| Festuca calligera | southwest fescue | Poaceae | |
| Festuca earlei | Earle's fescue | Poaceae | |
| Festuca idahoensis | Idaho fescue | Poaceae | |
| Festuca idahoensis ssp. idahoensis | Idaho fescue | Poaceae | |
| Festuca minutiflora | smallflower fescue | Poaceae | |
| Festuca rubra | red fescue | Poaceae | |
| Festuca rubra ssp. rubra | red fescue | Poaceae | |
| Festuca saximontana | Rocky Mountain fescue | Poaceae | |
| Festuca saximontana var. saximontana | Rocky Mountain fescue | Poaceae | |
| Festuca sororia | ravine fescue | Poaceae | |
| Festuca thurberi | Thurber's fescue | Poaceae | |
| Festuca valesiaca | Volga fescue | Poaceae | |
| Fimbristylis | fimbry | Cyperaceae | |
| Fimbristylis annua | annual fimbry | Cyperaceae | |
| Fimbristylis thermalis | hot springs fimbry | Cyperaceae | |
| Fimbristylis vahlii | Vahl's fimbry | Cyperaceae | |
| Fingerhuthia | Zulu fescue | Poaceae | |
| Fingerhuthia africana | Zulu fescue | Poaceae | |
| Flaveria | yellowtops | Asteraceae | |
| Flaveria campestris | alkali yellowtops | Asteraceae | |
| Flaveria macdougalii | Mcdougall's yellowtops | Asteraceae | |
| Flaveria trinervia | clustered yellowtops | Asteraceae | |
| Fleischmannia | thoroughwort | Asteraceae | |
| Fleischmannia incarnata | pink thoroughwort | Asteraceae | |
| Fleischmannia pycnocephala | lavender thoroughwort | Asteraceae | |
| Fleischmannia sonorae | Sonoran thoroughwort | Asteraceae | |
| Flourensia | tarwort | Asteraceae | |
| Flourensia cernua | American tarwort | Asteraceae | |
| Foeniculum | fennel | Apiaceae | |
| Foeniculum vulgare | sweet fennel | Apiaceae | |
| Forestiera | swampprivet | Oleaceae | |
| Forestiera pubescens | stretchberry | Oleaceae | |
| Forestiera pubescens var. pubescens | stretchberry | Oleaceae | |
| Forestiera shrevei | desert olive | Oleaceae | |
| Fouquieria | ocotillo | Fouquieriaceae | |
| Fouquieria splendens | ocotillo | Fouquieriaceae | |
| Fragaria | strawberry | Rosaceae | |
| Fragaria vesca | woodland strawberry | Rosaceae | |
| Fragaria vesca ssp. bracteata | woodland strawberry | Rosaceae | |
| Fragaria virginiana | Virginia strawberry | Rosaceae | |
| Fragaria virginiana ssp. glauca | Virginia strawberry | Rosaceae | |
| Fragaria virginiana ssp. platypetala | Virginia strawberry | Rosaceae | |
| Frangula | buckthorn | Rhamnaceae | |
| Frangula betulifolia | beechleaf frangula | Rhamnaceae | |
| Frangula betulifolia ssp. betulifolia | beechleaf frangula | Rhamnaceae | |
| Frangula betulifolia ssp. obovata | obovate buckthorn | Rhamnaceae | |
| Frangula blumeri | Rhamnaceae | ||
| Frangula californica | California buckthorn | Rhamnaceae | |
| Frangula californica ssp. ursina | California buckthorn | Rhamnaceae | |
| Frasera | green gentian | Gentianaceae | |
| Frasera albomarginata | desert frasera | Gentianaceae | |
| Frasera paniculata | tufted frasera | Gentianaceae | |
| Frasera parryi | Coahuila frasera | Gentianaceae | |
| Frasera speciosa | elkweed | Gentianaceae | |
| Fraxinus | ash | Oleaceae | |
| Fraxinus anomala | singleleaf ash | Oleaceae | |
| Fraxinus anomala var. anomala | singleleaf ash | Oleaceae | |
| Fraxinus anomala var. lowellii | singleleaf ash | Oleaceae | |
| Fraxinus cuspidata | fragrant ash | Oleaceae | |
| Fraxinus dipetala | California ash | Oleaceae | |
| Fraxinus gooddingii | Goodding's ash | Oleaceae | |
| Fraxinus greggii | Gregg's ash | Oleaceae | |
| Fraxinus papillosa | Chihuahuan ash | Oleaceae | |
| Fraxinus velutina | velvet ash | Oleaceae | |
| Fremontodendron | flannelbush | Sterculiaceae | |
| Fremontodendron californicum | California flannelbush | Sterculiaceae | |
| Fritillaria | fritillary | Liliaceae | |
| Fritillaria atropurpurea | spotted fritillary | Liliaceae | |
| Froelichia | snakecotton | Amaranthaceae | |
| Froelichia arizonica | Arizona snakecotton | Amaranthaceae | |
| Froelichia gracilis | slender snakecotton | Amaranthaceae | |
| Froelichia interrupta | Texas snakecotton | Amaranthaceae | |
| Fuirena | umbrella-sedge | Cyperaceae | |
| Fuirena simplex | western umbrella-sedge | Cyperaceae | |
| Fuirena simplex var. simplex | western umbrella-sedge | Cyperaceae | |
| Fumaria | fumitory | Fumariaceae | |
| Fumaria occidentalis | western fumitory | Fumariaceae | |
| Fumaria parviflora | fineleaf fumitory | Fumariaceae | |
| Funastrum | twinevine | Asclepiadaceae | |
| Funastrum crispum | wavyleaf twinevine | Asclepiadaceae | |
| Funastrum cynanchoides | fringed twinevine | Asclepiadaceae | |
| Funastrum cynanchoides ssp. cynanchoides | fringed twinevine | Asclepiadaceae | |
| Funastrum cynanchoides ssp. heterophyllum | Hartweg's twinevine | Asclepiadaceae | |
| Funastrum hirtellum | hairy milkweed | Asclepiadaceae | |
| G | |||
| Gaillardia | blanketflower | Asteraceae | |
| Gaillardia aristata | common gaillardia | Asteraceae | |
| Gaillardia arizonica | Arizona blanketflower | Asteraceae | |
| Gaillardia multiceps | onion blanketflower | Asteraceae | |
| Gaillardia multiceps var. multiceps | onion blanketflower | Asteraceae | |
| Gaillardia parryi | Parry's blanketflower | Asteraceae | |
| Gaillardia pinnatifida | red dome blanketflower | Asteraceae | |
| Gaillardia pinnatifida var. linearis | red dome blanketflower | Asteraceae | |
| Gaillardia pinnatifida var. pinnatifida | red dome blanketflower | Asteraceae | |
| Gaillardia pulchella | firewheel | Asteraceae | |
| Gaillardia pulchella var. pulchella | firewheel | Asteraceae | |
| Galactia | milkpea | Fabaceae | |
| Galactia wrightii | Wright's milkpea | Fabaceae | |
| Galactia wrightii var. mollissima | Wright's milkpea | Fabaceae | |
| Galactia wrightii var. wrightii | Wright's milkpea | Fabaceae | |
| Galinsoga | gallant soldier | Asteraceae | |
| Galinsoga parviflora | gallant soldier | Asteraceae | |
| Galium | bedstraw | Rubiaceae | |
| Galium aparine | stickywilly | Rubiaceae | |
| Galium bifolium | twinleaf bedstraw | Rubiaceae | |
| Galium boreale | northern bedstraw | Rubiaceae | |
| Galium collomiae | Fossil Hill Creek bedstraw | Rubiaceae | |
| Galium coloradoense | Colorado bedstraw | Rubiaceae | |
| Galium fendleri | Fendler's bedstraw | Rubiaceae | |
| Galium mexicanum | Mexican bedstraw | Rubiaceae | |
| Galium mexicanum ssp. asperrimum | Mexican bedstraw | Rubiaceae | |
| Galium microphyllum | bracted bedstraw | Rubiaceae | |
| Galium munzii | Munz's bedstraw | Rubiaceae | |
| Galium munzii ssp. ambivalens | Munz's bedstraw | Rubiaceae | |
| Galium munzii ssp. munzii | Munz's bedstraw | Rubiaceae | |
| Galium proliferum | limestone bedstraw | Rubiaceae | |
| Galium stellatum | starry bedstraw | Rubiaceae | |
| Galium stellatum ssp. eremicum | starry bedstraw | Rubiaceae | |
| Galium trifidum | threepetal bedstraw | Rubiaceae | |
| Galium trifidum ssp. subbiflorum | threepetal bedstraw | Rubiaceae | |
| Galium triflorum | fragrant bedstraw | Rubiaceae | |
| Galium uncinulatum | bristly bedstraw | Rubiaceae | |
| Galium wrightii | Wright's bedstraw | Rubiaceae | |
| Gamochaeta | everlasting | Asteraceae | |
| Gamochaeta falcata | narrowleaf purple everlasting | Asteraceae | |
| Gamochaeta purpurea | spoonleaf purple everlasting | Asteraceae | |
| Garrya | silktassel | Garryaceae | |
| Garrya flavescens | ashy silktassel | Garryaceae | |
| Garrya wrightii | Wright's silktassel | Garryaceae | |
| Gastridium | nit grass | Poaceae | |
| Gastridium phleoides | nit grass | Poaceae | |
| Gaura | beeblossom | Onagraceae | |
| Gaura coccinea | scarlet beeblossom | Onagraceae | |
| Gaura hexandra | harlequinbush | Onagraceae | |
| Gaura hexandra ssp. gracilis | harlequinbush | Onagraceae | |
| Gaura mollis | velvetweed | Onagraceae | |
| Gayophytum | groundsmoke | Onagraceae | |
| Gayophytum decipiens | deceptive groundsmoke | Onagraceae | |
| Gayophytum diffusum | spreading groundsmoke | Onagraceae | |
| Gayophytum diffusum ssp. parviflorum | spreading groundsmoke | Onagraceae | |
| Gayophytum racemosum | blackfoot groundsmoke | Onagraceae | |
| Gayophytum ramosissimum | pinyon groundsmoke | Onagraceae | |
| Gentiana | gentian | Gentianaceae | |
| Gentiana affinis | pleated gentian | Gentianaceae | |
| Gentiana fremontii | moss gentian | Gentianaceae | |
| Gentianella | dwarf gentian | Gentianaceae | |
| Gentianella amarella | autumn dwarf gentian | Gentianaceae | |
| Gentianella amarella ssp. acuta | autumn dwarf gentian | Gentianaceae | |
| Gentianella amarella ssp. heterosepala | autumn dwarf gentian | Gentianaceae | |
| Gentianella microcalyx | Chiricahua dwarf gentian | Gentianaceae | |
| Gentianella tenella | Dane's dwarf gentian | Gentianaceae | |
| Gentianella tenella ssp. tenella | Dane's dwarf gentian | Gentianaceae | |
| Gentianella wislizeni | Chiricahua Mountain dwarf gentian | Gentianaceae | |
| Gentianella wrightii | Wright's dwarf gentian | Gentianaceae | |
| Gentianopsis | fringed gentian | Gentianaceae | |
| Gentianopsis barbellata | perennial fringed gentian | Gentianaceae | |
| Gentianopsis macrantha | grand fringed gentian | Gentianaceae | |
| Geraea | desertsunflower | Asteraceae | |
| Geraea canescens | hairy desertsunflower | Asteraceae | |
| Geranium | geranium | Geraniaceae | |
| Geranium atropurpureum | western purple cranesbill | Geraniaceae | |
| Geranium atropurpureum var. atropurpureum | western purple cranesbill | Geraniaceae | |
| Geranium caespitosum | pineywoods geranium | Geraniaceae | |
| Geranium caespitosum var. caespitosum | pineywoods geranium | Geraniaceae | |
| Geranium caespitosum var. eremophilum | purple cluster geranium | Geraniaceae | |
| Geranium caespitosum var. fremontii | Fremont's geranium | Geraniaceae | |
| Geranium caespitosum var. parryi | Parry's geranium | Geraniaceae | |
| Geranium carolinianum | Carolina geranium | Geraniaceae | |
| Geranium carolinianum var. carolinianum | Carolina geranium | Geraniaceae | |
| Geranium lentum | Mogollon geranium | Geraniaceae | |
| Geranium richardsonii | Richardson's geranium | Geraniaceae | |
| Geranium wislizeni | Huachuca Mountain geranium | Geraniaceae | |
| Geum | avens | Rosaceae | |
| Geum aleppicum | yellow avens | Rosaceae | |
| Geum macrophyllum | largeleaf avens | Rosaceae | |
| Geum macrophyllum var. perincisum | largeleaf avens | Rosaceae | |
| Geum rossii | Ross' avens | Rosaceae | |
| Geum rossii var. turbinatum | Ross' avens | Rosaceae | |
| Geum triflorum | old man's whiskers | Rosaceae | |
| Geum triflorum var. ciliatum | old man's whiskers | Rosaceae | |
| Gilia | gilia | Polemoniaceae | |
| Gilia achilleifolia | California gilia | Polemoniaceae | |
| Gilia achilleifolia ssp. multicaulis | California gilia | Polemoniaceae | |
| Gilia capitata | bluehead gilia | Polemoniaceae | |
| Gilia capitata ssp. staminea | bluehead gilia | Polemoniaceae | |
| Gilia clivorum | purplespot gilia | Polemoniaceae | |
| Gilia clokeyi | Clokey's gilia | Polemoniaceae | |
| Gilia flavocincta | lesser yellowthroat gilia | Polemoniaceae | |
| Gilia flavocincta ssp. australis | lesser yellowthroat gilia | Polemoniaceae | |
| Gilia flavocincta ssp. flavocincta | lesser yellowthroat gilia | Polemoniaceae | |
| Gilia mexicana | El Paso gilia | Polemoniaceae | |
| Gilia minor | little gilia | Polemoniaceae | |
| Gilia ophthalmoides | eyed gilia | Polemoniaceae | |
| Gilia scopulorum | rock gilia | Polemoniaceae | |
| Gilia sinuata | rosy gilia | Polemoniaceae | |
| Gilia stellata | star gilia | Polemoniaceae | |
| Gilia transmontana | transmontane gilia | Polemoniaceae | |
| Giliastrum | Polemoniaceae | ||
| Giliastrum acerosum | bluebowls | Polemoniaceae | |
| Glandularia | mock vervain | Verbenaceae | |
| Glandularia bipinnatifida | Dakota mock vervain | Verbenaceae | |
| Glandularia bipinnatifida var. bipinnatifida | Dakota mock vervain | Verbenaceae | |
| Glandularia bipinnatifida var. ciliata | Davis Mountain mock vervain | Verbenaceae | |
| Glandularia chiricahensis | Chiricahua Mountain mock vervain | Verbenaceae | |
| Glandularia elegans | mountain mock vervain | Verbenaceae | |
| Glandularia elegans var. asperata | mountain mock vervain | Verbenaceae | |
| Glandularia elegans var. elegans | mountain mock vervain | Verbenaceae | |
| Glandularia gooddingii | southwestern mock vervain | Verbenaceae | |
| Glandularia hybrida | Verbenaceae | ||
| Glandularia pulchella | South American mock vervain | Verbenaceae | |
| Glebionis | Asteraceae | ||
| Glebionis coronarium | crowndaisy | Asteraceae | |
| Gleditsia | locust | Fabaceae | |
| Gleditsia triacanthos | honeylocust | Fabaceae | |
| Glinus | sweetjuice | Molluginaceae | |
| Glinus lotoides | lotus sweetjuice | Molluginaceae | |
| Glinus radiatus | spreading sweetjuice | Molluginaceae | |
| Glossopetalon | greasebush | Crossosomataceae | |
| Glossopetalon spinescens | spiny greasebush | Crossosomataceae | |
| Glossopetalon spinescens var. aridum | spiny greasebush | Crossosomataceae | |
| Glossopetalon spinescens var. meionandrum | spiny greasebush | Crossosomataceae | |
| Glossopetalon spinescens var. microphyllum | spiny greasebush | Crossosomataceae | |
| Glossopetalon spinescens var. spinescens | spiny greasebush | Crossosomataceae | |
| Glyceria | mannagrass | Poaceae | |
| Glyceria borealis | small floating mannagrass | Poaceae | |
| Glyceria grandis | American mannagrass | Poaceae | |
| Glyceria grandis var. grandis | American mannagrass | Poaceae | |
| Glyceria striata | fowl mannagrass | Poaceae | |
| Glycyrrhiza | licorice | Fabaceae | |
| Glycyrrhiza lepidota | American licorice | Fabaceae | |
| Glyptopleura | glyptopleura | Asteraceae | |
| Glyptopleura marginata | carveseed | Asteraceae | |
| Glyptopleura setulosa | holy dandelion | Asteraceae | |
| Gnaphalium | cudweed | Asteraceae | |
| Gnaphalium exilifolium | slender cudweed | Asteraceae | |
| Gnaphalium palustre | western marsh cudweed | Asteraceae | |
| Gomphrena | globe amaranth | Amaranthaceae | |
| Gomphrena caespitosa | tufted globe amaranth | Amaranthaceae | |
| Gomphrena nitida | pearly globe amaranth | Amaranthaceae | |
| Gomphrena sonorae | Sonoran globe amaranth | Amaranthaceae | |
| Goodyera | rattlesnake plantain | Orchidaceae | |
| Goodyera oblongifolia | western rattlesnake plantain | Orchidaceae | |
| Goodyera repens | lesser rattlesnake plantain | Orchidaceae | |
| Gossypium | cotton | Malvaceae | |
| Gossypium thurberi | Thurber's cotton | Malvaceae | |
| Graptopetalum | leatherpetal | Crassulaceae | |
| Graptopetalum bartramii | Patagonia Mountain leatherpetal | Crassulaceae | |
| Graptopetalum rusbyi | San Francisco River leatherpetal | Crassulaceae | |
| Gratiola | hedgehyssop | Scrophulariaceae | |
| Gratiola neglecta | clammy hedgehyssop | Scrophulariaceae | |
| Grayia | hopsage | Chenopodiaceae | |
| Grayia spinosa | spiny hopsage | Chenopodiaceae | |
| Grindelia | gumweed | Asteraceae | |
| Grindelia arizonica | Arizona gumweed | Asteraceae | |
| Grindelia arizonica var. arizonica | Arizona gumweed | Asteraceae | |
| Grindelia laciniata | cutleaf gumweed | Asteraceae | |
| Grindelia nuda | curlytop gumweed | Asteraceae | |
| Grindelia nuda var. aphanactis | curlytop gumweed | Asteraceae | |
| Grindelia oxylepis | Mexican gumweed | Asteraceae | |
| Grindelia papposa | Spanish gold | Asteraceae | |
| Grindelia squarrosa | curlycup gumweed | Asteraceae | |
| Grindelia squarrosa var. serrulata | curlycup gumweed | Asteraceae | |
| Grindelia squarrosa var. squarrosa | curlycup gumweed | Asteraceae | |
| Grusonia | Cactaceae | ||
| Grusonia clavata | club cholla | Cactaceae | |
| Grusonia emoryi | devil cholla | Cactaceae | |
| Grusonia kunzei | devil's cholla | Cactaceae | |
| Grusonia parishii | matted cholla | Cactaceae | |
| Guardiola | guardiola | Asteraceae | |
| Guardiola platyphylla | Apache plant | Asteraceae | |
| Guilleminea | matweed | Amaranthaceae | |
| Guilleminea densa | small matweed | Amaranthaceae | |
| Guilleminea densa var. aggregata | small matweed | Amaranthaceae | |
| Guilleminea densa var. densa | small matweed | Amaranthaceae | |
| Guillenia | mustard | Brassicaceae | |
| Guillenia lasiophylla | California mustard | Brassicaceae | |
| Gutierrezia | snakeweed | Asteraceae | |
| Gutierrezia arizonica | Arizona snakeweed | Asteraceae | |
| Gutierrezia microcephala | threadleaf snakeweed | Asteraceae | |
| Gutierrezia sarothrae | broom snakeweed | Asteraceae | |
| Gutierrezia serotina | late snakeweed | Asteraceae | |
| Gutierrezia sphaerocephala | roundleaf snakeweed | Asteraceae | |
| Gutierrezia wrightii | Wright's snakeweed | Asteraceae | |
| Gymnocarpium | oakfern | Dryopteridaceae | |
| Gymnocarpium dryopteris | western oakfern | Dryopteridaceae | |
| Gymnosperma | gymnosperma | Asteraceae | |
| Gymnosperma glutinosum | gumhead | Asteraceae | |
| H | |||
| Hackelia | stickseed | Boraginaceae | |
| Hackelia besseyi | Bessey's stickseed | Boraginaceae | |
| Hackelia floribunda | manyflower stickseed | Boraginaceae | |
| Hackelia pinetorum | Livermore stickseed | Boraginaceae | |
| Hackelia pinetorum var. pinetorum | Livermore stickseed | Boraginaceae | |
| Hackelia ursina | Chihuahuan stickseed | Boraginaceae | |
| Hackelia ursina var. diaboli | Chihuahuan stickseed | Boraginaceae | |
| Hackelia ursina var. pustulata | Chihuahuan stickseed | Boraginaceae | |
| Hackelia ursina var. ursina | Chihuahuan stickseed | Boraginaceae | |
| Hackelochloa | pitscale grass | Poaceae | |
| Hackelochloa granularis | pitscale grass | Poaceae | |
| Halenia | spurred gentian | Gentianaceae | |
| Halenia recurva | Mt. Graham spurred gentian | Gentianaceae | |
| Halimolobos | fissurewort | Brassicaceae | |
| Halimolobos diffusa | spreading fissurewort | Brassicaceae | |
| Halogeton | saltlover | Chenopodiaceae | |
| Halogeton glomeratus | saltlover | Chenopodiaceae | |
| Haplophyton | haplophyton | Apocynaceae | |
| Haplophyton crooksii | cockroachplant | Apocynaceae | |
| Harpagonella | grapplinghook | Boraginaceae | |
| Harpagonella palmeri | Palmer's grapplinghook | Boraginaceae | |
| Harpagonella palmeri var. arizonica | Arizona grapplinghook | Boraginaceae | |
| Harpagonella palmeri var. palmeri | Palmer's grapplinghook | Boraginaceae | |
| Hedeoma | false pennyroyal | Lamiaceae | |
| Hedeoma costata | ribbed false pennyroyal | Lamiaceae | |
| Hedeoma costata var. pulchella | ribbed false pennyroyal | Lamiaceae | |
| Hedeoma dentata | dentate false pennyroyal | Lamiaceae | |
| Hedeoma diffusa | spreading false pennyroyal | Lamiaceae | |
| Hedeoma drummondii | Drummond's false pennyroyal | Lamiaceae | |
| Hedeoma hyssopifolia | aromatic false pennyroyal | Lamiaceae | |
| Hedeoma nana | dwarf false pennyroyal | Lamiaceae | |
| Hedeoma nana ssp. californica | California false pennyroyal | Lamiaceae | |
| Hedeoma nana ssp. macrocalyx | dwarf false pennyroyal | Lamiaceae | |
| Hedeoma nana ssp. nana | dwarf false pennyroyal | Lamiaceae | |
| Hedeoma oblongifolia | oblongleaf false pennyroyal | Lamiaceae | |
| Hedera | ivy | Araliaceae | |
| Hedera colchica | colchis ivy | Araliaceae | |
| Hedera helix | English ivy | Araliaceae | |
| Hedosyne | Asteraceae | ||
| Hedosyne ambrosiifolia | ragged marsh-elder | Asteraceae | |
| Hedyotis | starviolet | Rubiaceae | |
| Hedyotis greenei | Greene's starviolet | Rubiaceae | |
| Hedyotis vegrandis | New Mexico starviolet | Rubiaceae | |
| Hedypnois | hedypnois | Asteraceae | |
| Hedypnois cretica | Cretanweed | Asteraceae | |
| Hedysarum | sweetvetch | Fabaceae | |
| Hedysarum boreale | Utah sweetvetch | Fabaceae | |
| Hedysarum boreale ssp. boreale | Utah sweetvetch | Fabaceae | |
| Hedysarum boreale ssp. boreale var. boreale | Utah sweetvetch | Fabaceae | |
| Helenium | sneezeweed | Asteraceae | |
| Helenium arizonicum | Arizona sneezeweed | Asteraceae | |
| Helenium autumnale | common sneezeweed | Asteraceae | |
| Helenium autumnale var. autumnale | common sneezeweed | Asteraceae | |
| Helenium autumnale var. montanum | mountain sneezeweed | Asteraceae | |
| Helenium bigelovii | Bigelow's sneezeweed | Asteraceae | |
| Helenium thurberi | Thurber's sneezeweed | Asteraceae | |
| Helianthella | helianthella | Asteraceae | |
| Helianthella microcephala | purpledisk helianthella | Asteraceae | |
| Helianthella parryi | Parry's dwarf-sunflower | Asteraceae | |
| Helianthella quinquenervis | fivenerve helianthella | Asteraceae | |
| Helianthus | sunflower | Asteraceae | |
| Helianthus annuus | common sunflower | Asteraceae | |
| Helianthus anomalus | western sunflower | Asteraceae | |
| Helianthus arizonensis | Arizona sunflower | Asteraceae | |
| Helianthus ciliaris | Texas blueweed | Asteraceae | |
| Helianthus niveus | showy sunflower | Asteraceae | |
| Helianthus niveus ssp. canescens | showy sunflower | Asteraceae | |
| Helianthus niveus ssp. tephrodes | Algodones sunflower | Asteraceae | |
| Helianthus nuttallii | Nuttall's sunflower | Asteraceae | |
| Helianthus nuttallii ssp. nuttallii | Nuttall's sunflower | Asteraceae | |
| Helianthus pauciflorus | stiff sunflower | Asteraceae | |
| Helianthus pauciflorus ssp. subrhomboideus | stiff sunflower | Asteraceae | |
| Helianthus petiolaris | prairie sunflower | Asteraceae | |
| Helianthus petiolaris ssp. fallax | prairie sunflower | Asteraceae | |
| Helianthus petiolaris ssp. petiolaris | prairie sunflower | Asteraceae | |
| Heliomeris | false goldeneye | Asteraceae | |
| Heliomeris hispida | rough false goldeneye | Asteraceae | |
| Heliomeris longifolia | longleaf false goldeneye | Asteraceae | |
| Heliomeris longifolia var. annua | longleaf false goldeneye | Asteraceae | |
| Heliomeris longifolia var. longifolia | longleaf false goldeneye | Asteraceae | |
| Heliomeris multiflora | showy goldeneye | Asteraceae | |
| Heliomeris multiflora var. brevifolia | showy goldeneye | Asteraceae | |
| Heliomeris multiflora var. macrocephala | Asteraceae | ||
| Heliomeris multiflora var. multiflora | showy goldeneye | Asteraceae | |
| Heliomeris multiflora var. nevadensis | Nevada goldeneye | Asteraceae | |
| Heliopsis | heliopsis | Asteraceae | |
| Heliopsis parvifolia | mountain oxeye | Asteraceae | |
| Heliotropium | heliotrope | Boraginaceae | |
| Heliotropium convolvulaceum | phlox heliotrope | Boraginaceae | |
| Heliotropium convolvulaceum var. californicum | phlox heliotrope | Boraginaceae | |
| Heliotropium convolvulaceum var. convolvulaceum | phlox heliotrope | Boraginaceae | |
| Heliotropium curassavicum | salt heliotrope | Boraginaceae | |
| Heliotropium curassavicum var. curassavicum | salt heliotrope | Boraginaceae | |
| Heliotropium curassavicum var. oculatum | seaside heliotrope | Boraginaceae | |
| Heliotropium fruticosum | Key West heliotrope | Boraginaceae | |
| Heliotropium pringlei | Pringle's heliotrope | Boraginaceae | |
| Heliotropium procumbens | fourspike heliotrope | Boraginaceae | |
| Heliotropium procumbens var. procumbens | fourspike heliotrope | Boraginaceae | |
| Hemizonia | tarweed | Asteraceae | |
| Hemizonia kelloggii | Kellogg's tarweed | Asteraceae | |
| Henrya | henrya | Acanthaceae | |
| Henrya insularis | island renegade | Acanthaceae | |
| Heracleum | cowparsnip | Apiaceae | |
| Heracleum maximum | common cowparsnip | Apiaceae | |
| Herissantia | herissantia | Malvaceae | |
| Herissantia crispa | bladdermallow | Malvaceae | |
| Hermannia | hermannia | Sterculiaceae | |
| Hermannia pauciflora | Santa Catalina burstwort | Sterculiaceae | |
| Herniaria | rupturewort | Caryophyllaceae | |
| Herniaria hirsuta | hairy rupturewort | Caryophyllaceae | |
| Herniaria hirsuta ssp. cinerea | hairy rupturewort | Caryophyllaceae | |
| Hesperocallis | desert lily | Liliaceae | |
| Hesperocallis undulata | desert lily | Liliaceae | |
| Hesperochiron | hesperochiron | Hydrophyllaceae | |
| Hesperochiron pumilus | dwarf hesperochiron | Hydrophyllaceae | |
| Hesperodoria | glowweed | Asteraceae | |
| Hesperodoria salicina | willow glowweed | Asteraceae | |
| Hesperodoria scopulorum | Grand Canyon glowweed | Asteraceae | |
| Hesperostipa | needle and thread | Poaceae | |
| Hesperostipa comata | needle and thread | Poaceae | |
| Hesperostipa comata ssp. comata | needle and thread | Poaceae | |
| Hesperostipa comata ssp. intermedia | intermediate needle and thread | Poaceae | |
| Hesperostipa neomexicana | New Mexico feathergrass | Poaceae | |
| Hesperoyucca | Agavaceae | ||
| Hesperoyucca newberryi | Newberry's yucca | Agavaceae | |
| Hesperoyucca whipplei | chaparral yucca | Agavaceae | |
| Heteranthera | mudplantain | Pontederiaceae | |
| Heteranthera dubia | grassleaf mudplantain | Pontederiaceae | |
| Heteranthera limosa | blue mudplantain | Pontederiaceae | |
| Heteranthera peduncularis | egret mudplantain | Pontederiaceae | |
| Heteranthera rotundifolia | roundleaf mudplantain | Pontederiaceae | |
| Heteropogon | tanglehead | Poaceae | |
| Heteropogon contortus | tanglehead | Poaceae | |
| Heteropogon melanocarpus | sweet tanglehead | Poaceae | |
| Heterosperma | heterosperma | Asteraceae | |
| Heterosperma pinnatum | wingpetal | Asteraceae | |
| Heterotheca | false goldenaster | Asteraceae | |
| Heterotheca fulcrata | rockyscree false goldenaster | Asteraceae | |
| Heterotheca fulcrata var. amplifolia | rockyscree false goldenaster | Asteraceae | |
| Heterotheca fulcrata var. arizonica | Arizona false goldenaster | Asteraceae | |
| Heterotheca fulcrata var. fulcrata | rockyscree false goldenaster | Asteraceae | |
| Heterotheca fulcrata var. senilis | rockyscree false goldenaster | Asteraceae | |
| Heterotheca grandiflora | telegraphweed | Asteraceae | |
| Heterotheca marginata | Sonora false goldenaster | Asteraceae | |
| Heterotheca rutteri | Rutter's false goldenaster | Asteraceae | |
| Heterotheca subaxillaris | camphorweed | Asteraceae | |
| Heterotheca villosa | hairy false goldenaster | Asteraceae | |
| Heterotheca villosa var. minor | hairy false goldenaster | Asteraceae | |
| Heterotheca villosa var. nana | hairy false goldenaster | Asteraceae | |
| Heterotheca villosa var. pedunculata | hairy false goldenaster | Asteraceae | |
| Heterotheca villosa var. scabra | hairy false goldenaster | Asteraceae | |
| Heterotheca viscida | cliff false goldenaster | Asteraceae | |
| Heterotheca zionensis | Zion false goldenaster | Asteraceae | |
| Heuchera | alumroot | Saxifragaceae | |
| Heuchera eastwoodiae | Senator Mine alumroot | Saxifragaceae | |
| Heuchera glomerulata | Chiricahua Mountain alumroot | Saxifragaceae | |
| Heuchera novomexicana | New Mexico alumroot | Saxifragaceae | |
| Heuchera parvifolia | littleleaf alumroot | Saxifragaceae | |
| Heuchera parvifolia var. arizonica | Arizona alumroot | Saxifragaceae | |
| Heuchera parvifolia var. flavescens | littleleaf alumroot | Saxifragaceae | |
| Heuchera rubescens | pink alumroot | Saxifragaceae | |
| Heuchera rubescens var. rubescens | pink alumroot | Saxifragaceae | |
| Heuchera rubescens var. versicolor | pink alumroot | Saxifragaceae | |
| Heuchera sanguinea | coralbells | Saxifragaceae | |
| Heuchera sanguinea var. pulchra | coralbells | Saxifragaceae | |
| Heuchera sanguinea var. sanguinea | coralbells | Saxifragaceae | |
| Hexalectris | crested coralroot | Orchidaceae | |
| Hexalectris revoluta | Chisos Mountain crested coralroot | Orchidaceae | |
| Hexalectris spicata | spiked crested coralroot | Orchidaceae | |
| Hexalectris spicata var. arizonica | spiked crested coralroot | Orchidaceae | |
| Hexalectris spicata var. spicata | spiked crested coralroot | Orchidaceae | |
| Hexalectris warnockii | Texas crested coralroot | Orchidaceae | |
| Hibiscus | rosemallow | Malvaceae | |
| Hibiscus biseptus | Arizona rosemallow | Malvaceae | |
| Hibiscus coulteri | desert rosemallow | Malvaceae | |
| Hibiscus denudatus | paleface | Malvaceae | |
| Hibiscus trionum | flower of an hour | Malvaceae | |
| Hieracium | hawkweed | Asteraceae | |
| Hieracium carneum | Huachuca hawkweed | Asteraceae | |
| Hieracium fendleri | yellow hawkweed | Asteraceae | |
| Hieracium fendleri var. discolor | yellow hawkweed | Asteraceae | |
| Hieracium fendleri var. fendleri | yellow hawkweed | Asteraceae | |
| Hieracium fendleri var. mogollense | Mogollon hawkweed | Asteraceae | |
| Hieracium lemmonii | Lemmon's hawkweed | Asteraceae | |
| Hieracium pringlei | Pringle's hawkweed | Asteraceae | |
| Hieracium rusbyi | Rusby's hawkweed | Asteraceae | |
| Hierochloe | sweetgrass | Poaceae | |
| Hierochloe hirta | northern sweetgrass | Poaceae | |
| Hierochloe hirta ssp. arctica | northern sweetgrass | Poaceae | |
| Hilaria | curly-mesquite | Poaceae | |
| Hilaria belangeri | curly-mesquite | Poaceae | |
| Hilaria belangeri var. belangeri | curly-mesquite | Poaceae | |
| Hilaria belangeri var. longifolia | longleaf curly-mesquite | Poaceae | |
| Hippuris | mare's-tail | Hippuridaceae | |
| Hippuris vulgaris | common mare's-tail | Hippuridaceae | |
| Hoffmannseggia | rushpea | Fabaceae | |
| Hoffmannseggia drepanocarpa | sicklepod holdback | Fabaceae | |
| Hoffmannseggia glauca | Indian rushpea | Fabaceae | |
| Hoffmannseggia microphylla | wand holdback | Fabaceae | |
| Holcus | velvetgrass | Poaceae | |
| Holcus lanatus | common velvetgrass | Poaceae | |
| Holodiscus | oceanspray | Rosaceae | |
| Holodiscus discolor | oceanspray | Rosaceae | |
| Holodiscus dumosus | rockspirea | Rosaceae | |
| Hordeum | barley | Poaceae | |
| Hordeum arizonicum | Arizona barley | Poaceae | |
| Hordeum brachyantherum | meadow barley | Poaceae | |
| Hordeum brachyantherum ssp. brachyantherum | meadow barley | Poaceae | |
| Hordeum jubatum | foxtail barley | Poaceae | |
| Hordeum jubatum ssp. jubatum | foxtail barley | Poaceae | |
| Hordeum marinum | seaside barley | Poaceae | |
| Hordeum marinum ssp. gussonianum | Mediterranean barley | Poaceae | |
| Hordeum murinum | mouse barley | Poaceae | |
| Hordeum murinum ssp. glaucum | smooth barley | Poaceae | |
| Hordeum murinum ssp. leporinum | hare barley | Poaceae | |
| Hordeum murinum ssp. murinum | wall barley | Poaceae | |
| Hordeum pusillum | little barley | Poaceae | |
| Hordeum vulgare | common barley | Poaceae | |
| Hornungia | Brassicaceae | ||
| Hornungia procumbens | prostrate hutchinsia | Brassicaceae | |
| Horsfordia | velvetmallow | Malvaceae | |
| Horsfordia alata | pink velvetmallow | Malvaceae | |
| Horsfordia newberryi | Newberry's velvetmallow | Malvaceae | |
| Houstonia | bluet | Rubiaceae | |
| Houstonia pusilla | tiny bluet | Rubiaceae | |
| Houstonia rubra | red bluet | Rubiaceae | |
| Houstonia wrightii | pygmy bluet | Rubiaceae | |
| Hulsea | alpinegold | Asteraceae | |
| Hulsea heterochroma | redray alpinegold | Asteraceae | |
| Humulus | hop | Cannabaceae | |
| Humulus lupulus | common hop | Cannabaceae | |
| Humulus lupulus var. neomexicanus | common hop | Cannabaceae | |
| Hybanthus | greenviolet | Violaceae | |
| Hybanthus attenuatus | western greenviolet | Violaceae | |
| Hybanthus verticillatus | babyslippers | Violaceae | |
| Hydrilla | hydrilla | Hydrocharitaceae | |
| Hydrilla verticillata | waterthyme | Hydrocharitaceae | |
| Hydrocotyle | hydrocotyle | Apiaceae | |
| Hydrocotyle prolifera | whorled marshpennywort | Apiaceae | |
| Hydrocotyle ranunculoides | floating marshpennywort | Apiaceae | |
| Hydrocotyle verticillata | whorled marshpennywort | Apiaceae | |
| Hydrocotyle verticillata var. verticillata | whorled marshpennywort | Apiaceae | |
| Hydrophyllum | waterleaf | Hydrophyllaceae | |
| Hydrophyllum occidentale | western waterleaf | Hydrophyllaceae | |
| Hymenoclea | burrobrush | Asteraceae | |
| Hymenoclea monogyra | singlewhorl burrobrush | Asteraceae | |
| Hymenoclea salsola | burrobrush | Asteraceae | |
| Hymenoclea salsola var. fasciculata | burrobrush | Asteraceae | |
| Hymenoclea salsola var. pentalepis | burrobrush | Asteraceae | |
| Hymenoclea salsola var. salsola | burrobrush | Asteraceae | |
| Hymenopappus | hymenopappus | Asteraceae | |
| Hymenopappus filifolius | fineleaf hymenopappus | Asteraceae | |
| Hymenopappus filifolius var. cinereus | fineleaf hymenopappus | Asteraceae | |
| Hymenopappus filifolius var. lugens | fineleaf hymenopappus | Asteraceae | |
| Hymenopappus filifolius var. megacephalus | fineleaf hymenopappus | Asteraceae | |
| Hymenopappus filifolius var. nanus | fineleaf hymenopappus | Asteraceae | |
| Hymenopappus filifolius var. pauciflorus | fineleaf hymenopappus | Asteraceae | |
| Hymenopappus filifolius var. tomentosus | finehair hymenopappus | Asteraceae | |
| Hymenopappus flavescens | collegeflower | Asteraceae | |
| Hymenopappus flavescens var. canotomentosus | collegeflower | Asteraceae | |
| Hymenopappus mexicanus | Mexican woollywhite | Asteraceae | |
| Hymenopappus radiatus | ray hymenopappus | Asteraceae | |
| Hymenothrix | thimblehead | Asteraceae | |
| Hymenothrix loomisii | Loomis' thimblehead | Asteraceae | |
| Hymenothrix wislizeni | Trans-Pecos thimblehead | Asteraceae | |
| Hymenothrix wrightii | Wright's thimblehead | Asteraceae | |
| Hymenoxys | rubberweed | Asteraceae | |
| Hymenoxys ambigens | Pinaleno Mountain rubberweed | Asteraceae | |
| Hymenoxys ambigens var. ambigens | Pinaleno Mountain rubberweed | Asteraceae | |
| Hymenoxys ambigens var. floribunda | Apache Passe rubberweed | Asteraceae | |
| Hymenoxys bigelovii | Bigelow's rubberweed | Asteraceae | |
| Hymenoxys cooperi | Cooper's rubberweed | Asteraceae | |
| Hymenoxys cooperi var. canescens | Cooper's rubberweed | Asteraceae | |
| Hymenoxys cooperi var. cooperi | Cooper's rubberweed | Asteraceae | |
| Hymenoxys helenioides | Intermountain rubberweed | Asteraceae | |
| Hymenoxys hoopesii | owl's-claws | Asteraceae | |
| Hymenoxys jamesii | Jame's rubberweed | Asteraceae | |
| Hymenoxys lemmonii | Lemmon's rubberweed | Asteraceae | |
| Hymenoxys odorata | bitter rubberweed | Asteraceae | |
| Hymenoxys quinquesquamata | rincon rubberweed | Asteraceae | |
| Hymenoxys richardsonii | pingue rubberweed | Asteraceae | |
| Hymenoxys richardsonii var. floribunda | Colorado rubberweed | Asteraceae | |
| Hymenoxys rusbyi | Rusby's rubberweed | Asteraceae | |
| Hymenoxys subintegra | Arizona rubberweed | Asteraceae | |
| Hypericum | St. Johnswort | Clusiaceae | |
| Hypericum anagalloides | tinker's penny | Clusiaceae | |
| Hypericum scouleri | Scouler's St. Johnswort | Clusiaceae | |
| Hypericum scouleri ssp. scouleri | Scouler's St. Johnswort | Clusiaceae | |
| Hypoxis | star-grass | Liliaceae | |
| Hypoxis mexicana | Mexican yellow star-grass | Liliaceae | |
| Hyptis | bushmint | Lamiaceae | |
| Hyptis emoryi | desert lavender | Lamiaceae | |
| I | |||
| Ibervillea | globeberry | Cucurbitaceae | |
| Ibervillea tenuisecta | slimlobe globeberry | Cucurbitaceae | |
| Iliamna | wild hollyhock | Malvaceae | |
| Iliamna grandiflora | largeflower wild hollyhock | Malvaceae | |
| Imperata | satintail | Poaceae | |
| Imperata brevifolia | California satintail | Poaceae | |
| Indigofera | indigo | Fabaceae | |
| Indigofera sphaerocarpa | Sonoran indigo | Fabaceae | |
| Ipomoea | morning-glory | Convolvulaceae | |
| Ipomoea barbatisepala | canyon morning-glory | Convolvulaceae | |
| Ipomoea capillacea | purple morning-glory | Convolvulaceae | |
| Ipomoea cardiophylla | heartleaf morning-glory | Convolvulaceae | |
| Ipomoea costellata | crestrib morning-glory | Convolvulaceae | |
| Ipomoea cristulata | Trans-Pecos morning-glory | Convolvulaceae | |
| Ipomoea hederacea | ivyleaf morning-glory | Convolvulaceae | |
| Ipomoea leucantha | Convolvulaceae | ||
| Ipomoea longifolia | pinkthroat morning-glory | Convolvulaceae | |
| Ipomoea plummerae | Huachuca Mountain morning-glory | Convolvulaceae | |
| Ipomoea pubescens | silky morning-glory | Convolvulaceae | |
| Ipomoea purpurea | tall morning-glory | Convolvulaceae | |
| Ipomoea tenuiloba | spiderleaf | Convolvulaceae | |
| Ipomoea tenuiloba var. lemmonii | spiderleaf | Convolvulaceae | |
| Ipomoea ternifolia | tripleleaf morning-glory | Convolvulaceae | |
| Ipomoea ternifolia var. leptotoma | tripleleaf morning-glory | Convolvulaceae | |
| Ipomoea thurberi | Thurber's morning-glory | Convolvulaceae | |
| Ipomoea tricolor | grannyvine | Convolvulaceae | |
| Ipomopsis | ipomopsis | Polemoniaceae | |
| Ipomopsis aggregata | scarlet gilia | Polemoniaceae | |
| Ipomopsis aggregata ssp. formosissima | scarlet gilia | Polemoniaceae | |
| Ipomopsis arizonica | Arizona ipomopsis | Polemoniaceae | |
| Ipomopsis congesta | ballhead ipomopsis | Polemoniaceae | |
| Ipomopsis congesta ssp. frutescens | ballhead ipomopsis | Polemoniaceae | |
| Ipomopsis gunnisonii | sanddune ipomopsis | Polemoniaceae | |
| Ipomopsis laxiflora | iron ipomopsis | Polemoniaceae | |
| Ipomopsis longiflora | flaxflowered ipomopsis | Polemoniaceae | |
| Ipomopsis longiflora ssp. australis | whiteflower ipomopsis | Polemoniaceae | |
| Ipomopsis longiflora ssp. longiflora | flaxflowered ipomopsis | Polemoniaceae | |
| Ipomopsis macombii | Macomb's ipomopsis | Polemoniaceae | |
| Ipomopsis macrosiphon | longtube ipomopsis | Polemoniaceae | |
| Ipomopsis multiflora | manyflowered ipomopsis | Polemoniaceae | |
| Ipomopsis polycladon | manybranched ipomopsis | Polemoniaceae | |
| Ipomopsis pumila | dwarf ipomopsis | Polemoniaceae | |
| Ipomopsis tenuifolia | slenderleaf skyrocket | Polemoniaceae | |
| Ipomopsis tenuituba | slendertube skyrocket | Polemoniaceae | |
| Ipomopsis tenuituba ssp. latiloba | slendertube skyrocket | Polemoniaceae | |
| Ipomopsis thurberi | El Paso skyrocket | Polemoniaceae | |
| Iresine | bloodleaf | Amaranthaceae | |
| Iresine heterophylla | Standley's bloodleaf | Amaranthaceae | |
| Iris | iris | Iridaceae | |
| Iris missouriensis | Rocky Mountain iris | Iridaceae | |
| Isocoma | goldenbush | Asteraceae | |
| Isocoma acradenia | alkali goldenbush | Asteraceae | |
| Isocoma acradenia var. acradenia | alkali goldenbush | Asteraceae | |
| Isocoma acradenia var. eremophila | alkali goldenbush | Asteraceae | |
| Isocoma azteca | Aztec goldenbush | Asteraceae | |
| Isocoma pluriflora | southern goldenbush | Asteraceae | |
| Isocoma rusbyi | Rusby's goldenbush | Asteraceae | |
| Isocoma tenuisecta | burroweed | Asteraceae | |
| Isoetes | quillwort | Isoetaceae | |
| Isoetes bolanderi | Bolander's quillwort | Isoetaceae | |
| Iva | marsh elder | Asteraceae | |
| Iva axillaris | povertyweed | Asteraceae | |
| Ivesia | mousetail | Rosaceae | |
| Ivesia arizonica | rock whitefeather | Rosaceae | |
| Ivesia arizonica var. arizonica | Arizona whitefeather | Rosaceae | |
| Ivesia arizonica var. saxosa | rock whitefeather | Rosaceae | |
| Ivesia multifoliolata | manyleaf mousetail | Rosaceae | |
| Ivesia sabulosa | Intermountain mousetail | Rosaceae | |
| J | |||
| Jacquemontia | clustervine | Convolvulaceae | |
| Jacquemontia agrestis | midnightblue clustervine | Convolvulaceae | |
| Jacquemontia pringlei | Pringle's clustervine | Convolvulaceae | |
| Jaltomata | false holly | Solanaceae | |
| Jaltomata procumbens | creeping false holly | Solanaceae | |
| Jamesia | cliffbush | Hydrangeaceae | |
| Jamesia americana | fivepetal cliffbush | Hydrangeaceae | |
| Jamesia americana var. americana | fivepetal cliffbush | Hydrangeaceae | |
| Janusia | janusia | Malpighiaceae | |
| Janusia gracilis | slender janusia | Malpighiaceae | |
| Jatropha | nettlespurge | Euphorbiaceae | |
| Jatropha cardiophylla | sangre de cristo | Euphorbiaceae | |
| Jatropha cinerea | Arizona nettlespurge | Euphorbiaceae | |
| Jatropha cuneata | physicnut | Euphorbiaceae | |
| Jatropha macrorhiza | ragged nettlespurge | Euphorbiaceae | |
| Jatropha macrorhiza var. septemfida | ragged nettlespurge | Euphorbiaceae | |
| Juglans | walnut | Juglandaceae | |
| Juglans major | Arizona walnut | Juglandaceae | |
| Juncus | rush | Juncaceae | |
| Juncus acuminatus | tapertip rush | Juncaceae | |
| Juncus acutus | spiny rush | Juncaceae | |
| Juncus acutus ssp. leopoldii | Leopold's rush | Juncaceae | |
| Juncus ambiguus | seasice rush | Juncaceae | |
| Juncus arcticus | arctic rush | Juncaceae | |
| Juncus arcticus ssp. littoralis | mountain rush | Juncaceae | |
| Juncus articulatus | jointleaf rush | Juncaceae | |
| Juncus brevicaudatus | narrowpanicle rush | Juncaceae | |
| Juncus bufonius | toad rush | Juncaceae | |
| Juncus bufonius var. bufonius | toad rush | Juncaceae | |
| Juncus bufonius var. occidentalis | toad rush | Juncaceae | |
| Juncus confusus | Colorado rush | Juncaceae | |
| Juncus cooperi | Cooper's rush | Juncaceae | |
| Juncus drummondii | Drummond's rush | Juncaceae | |
| Juncus drummondii var. drummondii | Drummond's rush | Juncaceae | |
| Juncus dudleyi | Dudley's rush | Juncaceae | |
| Juncus effusus | common rush | Juncaceae | |
| Juncus effusus var. brunneus | lamp rush | Juncaceae | |
| Juncus effusus var. exiguus | lamp rush | Juncaceae | |
| Juncus effusus var. pacificus | Pacific rush | Juncaceae | |
| Juncus ensifolius | swordleaf rush | Juncaceae | |
| Juncus interior | inland rush | Juncaceae | |
| Juncus interior var. arizonicus | Arizona rush | Juncaceae | |
| Juncus interior var. interior | inland rush | Juncaceae | |
| Juncus interior var. neomexicanus | New Mexico rush | Juncaceae | |
| Juncus longistylis | longstyle rush | Juncaceae | |
| Juncus longistylis var. longistylis | longstyle rush | Juncaceae | |
| Juncus longistylis var. scabratus | longstyle rush | Juncaceae | |
| Juncus macrophyllus | longleaf rush | Juncaceae | |
| Juncus marginatus | grassleaf rush | Juncaceae | |
| Juncus mertensianus | Mertens' rush | Juncaceae | |
| Juncus mexicanus | Mexican rush | Juncaceae | |
| Juncus nevadensis | Sierra rush | Juncaceae | |
| Juncus nevadensis var. badius | Sierra rush | Juncaceae | |
| Juncus nodosus | knotted rush | Juncaceae | |
| Juncus nodosus var. nodosus | knotted rush | Juncaceae | |
| Juncus occidentalis | western rush | Juncaceae | |
| Juncus saximontanus | Rocky Mountain rush | Juncaceae | |
| Juncus tenuis | poverty rush | Juncaceae | |
| Juncus torreyi | Torrey's rush | Juncaceae | |
| Juncus tracyi | Tracy's rush | Juncaceae | |
| Juncus xiphioides | irisleaf rush | Juncaceae | |
| Juniperus | juniper | Cupressaceae | |
| Juniperus californica | California juniper | Cupressaceae | |
| Juniperus coahuilensis | redberry juniper | Cupressaceae | |
| Juniperus coahuilensis var. arizonica | redberry juniper | Cupressaceae | |
| Juniperus coahuilensis var. coahuilensis | redberry juniper | Cupressaceae | |
| Juniperus communis | common juniper | Cupressaceae | |
| Juniperus communis var. depressa | common juniper | Cupressaceae | |
| Juniperus deppeana | alligator juniper | Cupressaceae | |
| Juniperus monosperma | oneseed juniper | Cupressaceae | |
| Juniperus osteosperma | Utah juniper | Cupressaceae | |
| Juniperus scopulorum | Rocky Mountain juniper | Cupressaceae | |
| Justicia | water-willow | Acanthaceae | |
| Justicia californica | beloperone | Acanthaceae | |
| Justicia candicans | Arizona water-willow | Acanthaceae | |
| Justicia longii | longflower tube tongue | Acanthaceae | |
| Justicia sonorae | Sonoran water-willow | Acanthaceae | |
| K | |||
| Kallstroemia | caltrop | Zygophyllaceae | |
| Kallstroemia californica | California caltrop | Zygophyllaceae | |
| Kallstroemia grandiflora | Arizona poppy | Zygophyllaceae | |
| Kallstroemia hirsutissima | hairy caltrop | Zygophyllaceae | |
| Kallstroemia parviflora | warty caltrop | Zygophyllaceae | |
| Keckiella | keckiella | Scrophulariaceae | |
| Keckiella antirrhinoides | snapdragon penstemon | Scrophulariaceae | |
| Keckiella antirrhinoides ssp. microphylla | snapdragon penstemon | Scrophulariaceae | |
| Kelloggia | kelloggia | Rubiaceae | |
| Kelloggia galioides | milk kelloggia | Rubiaceae | |
| Koanophyllon | thoroughwort | Asteraceae | |
| Koanophyllon solidaginifolium | shrubby thoroughwort | Asteraceae | |
| Koeberlinia | allthorn | Capparaceae | |
| Koeberlinia spinosa | crown of thorns | Capparaceae | |
| Koeberlinia spinosa var. spinosa | crown of thorns | Capparaceae | |
| Koeberlinia spinosa var. tenuispina | crown of thorns | Capparaceae | |
| Koeleria | Junegrass | Poaceae | |
| Koeleria macrantha | prairie Junegrass | Poaceae | |
| Krameria | ratany | Krameriaceae | |
| Krameria erecta | littleleaf ratany | Krameriaceae | |
| Krameria grayi | white ratany | Krameriaceae | |
| Krameria lanceolata | trailing krameria | Krameriaceae | |
| Krascheninnikovia | winterfat | Chenopodiaceae | |
| Krascheninnikovia lanata | winterfat | Chenopodiaceae | |
| Krigia | dwarfdandelion | Asteraceae | |
| Krigia biflora | twoflower dwarfdandelion | Asteraceae | |
| Krigia biflora var. biflora | twoflower dwarfdandelion | Asteraceae | |
| Krigia biflora var. viridis | twoflower dwarfdandelion | Asteraceae | |
| L | |||
| Lactuca | lettuce | Asteraceae | |
| Lactuca graminifolia | grassleaf lettuce | Asteraceae | |
| Lactuca graminifolia var. arizonica | grassleaf lettuce | Asteraceae | |
| Lactuca ludoviciana | biannual lettuce | Asteraceae | |
| Lactuca saligna | willowleaf lettuce | Asteraceae | |
| Lactuca serriola | prickly lettuce | Asteraceae | |
| Lactuca tatarica | blue lettuce | Asteraceae | |
| Lactuca tatarica var. pulchella | blue lettuce | Asteraceae | |
| Laennecia | horseweed | Asteraceae | |
| Laennecia coulteri | Coulter's horseweed | Asteraceae | |
| Laennecia eriophylla | Cochise horseweed | Asteraceae | |
| Laennecia schiedeana | pineland horseweed | Asteraceae | |
| Laennecia sophiifolia | leafy horseweed | Asteraceae | |
| Lagascea | lagascea | Asteraceae | |
| Lagascea decipiens | doll's head | Asteraceae | |
| Lagenaria | lagenaria | Cucurbitaceae | |
| Lagenaria siceraria | bottle gourd | Cucurbitaceae | |
| Lamarckia | goldentop grass | Poaceae | |
| Lamarckia aurea | goldentop grass | Poaceae | |
| Lamium | deadnettle | Lamiaceae | |
| Lamium amplexicaule | henbit deadnettle | Lamiaceae | |
| Landoltia | Lemnaceae | ||
| Landoltia punctata | dotted duckmeat | Lemnaceae | |
| Langloisia | langloisia | Polemoniaceae | |
| Langloisia setosissima | Great Basin langloisia | Polemoniaceae | |
| Langloisia setosissima ssp. setosissima | Great Basin langloisia | Polemoniaceae | |
| Lantana | lantana | Verbenaceae | |
| Lantana achyranthifolia | brushland shrubverbena | Verbenaceae | |
| Lantana camara | lantana | Verbenaceae | |
| Lantana urticoides | West Indian shrubverbena | Verbenaceae | |
| Lappula | stickseed | Boraginaceae | |
| Lappula occidentalis | flatspine stickseed | Boraginaceae | |
| Lappula occidentalis var. cupulata | flatspine stickseed | Boraginaceae | |
| Lappula occidentalis var. occidentalis | flatspine stickseed | Boraginaceae | |
| Lappula squarrosa | European stickseed | Boraginaceae | |
| Lapsana | nipplewort | Asteraceae | |
| Lapsana communis | common nipplewort | Asteraceae | |
| Larrea | creosote bush | Zygophyllaceae | |
| Larrea tridentata | creosote bush | Zygophyllaceae | |
| Larrea tridentata var. tridentata | creosote bush | Zygophyllaceae | |
| Lasianthaea | lasianthaea | Asteraceae | |
| Lasianthaea podocephala | San Pedro daisy | Asteraceae | |
| Lasthenia | goldfields | Asteraceae | |
| Lasthenia californica | California goldfields | Asteraceae | |
| Lasthenia californica ssp. californica | California goldfields | Asteraceae | |
| Lathyrus | pea | Fabaceae | |
| Lathyrus brachycalyx | Bonneville pea | Fabaceae | |
| Lathyrus brachycalyx ssp. zionis | bush pea | Fabaceae | |
| Lathyrus eucosmus | bush vetchling | Fabaceae | |
| Lathyrus graminifolius | grassleaf pea | Fabaceae | |
| Lathyrus laetivirens | aspen pea | Fabaceae | |
| Lathyrus lanszwertii | Nevada pea | Fabaceae | |
| Lathyrus lanszwertii var. leucanthus | Nevada pea | Fabaceae | |
| Lathyrus latifolius | perennial pea | Fabaceae | |
| Lathyrus pauciflorus | fewflower pea | Fabaceae | |
| Lathyrus pauciflorus var. utahensis | Utah pea | Fabaceae | |
| Layia | tidytips | Asteraceae | |
| Layia glandulosa | whitedaisy tidytips | Asteraceae | |
| Layia platyglossa | coastal tidytips | Asteraceae | |
| Leersia | cutgrass | Poaceae | |
| Leersia oryzoides | rice cutgrass | Poaceae | |
| Leibnitzia | sunbonnets | Asteraceae | |
| Leibnitzia lyrata | Seeman's sunbonnets | Asteraceae | |
| Lemna | duckweed | Lemnaceae | |
| Lemna aequinoctialis | lesser duckweed | Lemnaceae | |
| Lemna gibba | swollen duckweed | Lemnaceae | |
| Lemna minor | common duckweed | Lemnaceae | |
| Lemna minuta | least duckweed | Lemnaceae | |
| Lemna obscura | little duckweed | Lemnaceae | |
| Lemna perpusilla | minute duckweed | Lemnaceae | |
| Lemna trisulca | star duckweed | Lemnaceae | |
| Lemna turionifera | turion duckweed | Lemnaceae | |
| Lemna valdiviana | valdivia duckweed | Lemnaceae | |
| Leontodon | hawkbit | Asteraceae | |
| Leontodon taraxacoides | lesser hawkbit | Asteraceae | |
| Leontodon taraxacoides ssp. taraxacoides | lesser hawkbit | Asteraceae | |
| Leonurus | motherwort | Lamiaceae | |
| Leonurus cardiaca | common motherwort | Lamiaceae | |
| Leonurus cardiaca ssp. cardiaca | common motherwort | Lamiaceae | |
| Lepidium | pepperweed | Brassicaceae | |
| Lepidium alyssoides | mesa pepperwort | Brassicaceae | |
| Lepidium alyssoides var. alyssoides | mesa pepperwort | Brassicaceae | |
| Lepidium alyssoides var. junceum | mesa pepperwort | Brassicaceae | |
| Lepidium campestre | field pepperweed | Brassicaceae | |
| Lepidium densiflorum | common pepperweed | Brassicaceae | |
| Lepidium densiflorum var. densiflorum | common pepperweed | Brassicaceae | |
| Lepidium densiflorum var. macrocarpum | bigseed pepperweed | Brassicaceae | |
| Lepidium densiflorum var. ramosum | miner's pepperweed | Brassicaceae | |
| Lepidium fremontii | desert pepperweed | Brassicaceae | |
| Lepidium fremontii var. fremontii | desert pepperweed | Brassicaceae | |
| Lepidium integrifolium | thickleaf pepperweed | Brassicaceae | |
| Lepidium integrifolium var. integrifolium | thickleaf pepperweed | Brassicaceae | |
| Lepidium lasiocarpum | shaggyfruit pepperweed | Brassicaceae | |
| Lepidium lasiocarpum var. lasiocarpum | shaggyfruit pepperweed | Brassicaceae | |
| Lepidium lasiocarpum var. wrightii | Wright's pepperweed | Brassicaceae | |
| Lepidium latifolium | broadleaved pepperweed | Brassicaceae | |
| Lepidium montanum | mountain pepperweed | Brassicaceae | |
| Lepidium montanum var. canescens | mountain pepperweed | Brassicaceae | |
| Lepidium montanum var. cinereum | mountain pepperweed | Brassicaceae | |
| Lepidium montanum var. glabrum | mountain pepperweed | Brassicaceae | |
| Lepidium montanum var. jonesii | Jones' pepperweed | Brassicaceae | |
| Lepidium montanum var. montanum | mountain pepperweed | Brassicaceae | |
| Lepidium oblongum | veiny pepperweed | Brassicaceae | |
| Lepidium oblongum var. oblongum | veiny pepperweed | Brassicaceae | |
| Lepidium perfoliatum | clasping pepperweed | Brassicaceae | |
| Lepidium ramosissimum | manybranched pepperweed | Brassicaceae | |
| Lepidium ramosissimum var. bourgeauanum | Bourgeau's pepperweed | Brassicaceae | |
| Lepidium thurberi | Thurber's pepperweed | Brassicaceae | |
| Lepidium virginicum | Virginia pepperweed | Brassicaceae | |
| Lepidium virginicum var. medium | intermediate pepperweed | Brassicaceae | |
| Lepidium virginicum var. pubescens | hairy pepperweed | Brassicaceae | |
| Lepidospartum | broomsage | Asteraceae | |
| Lepidospartum squamatum | California broomsage | Asteraceae | |
| Leptochloa | sprangletop | Poaceae | |
| Leptochloa dubia | green sprangletop | Poaceae | |
| Leptochloa fusca | Malabar sprangletop | Poaceae | |
| Leptochloa fusca ssp. fascicularis | bearded sprangletop | Poaceae | |
| Leptochloa fusca ssp. uninervia | Mexican sprangletop | Poaceae | |
| Leptochloa nealleyi | Nealley's sprangletop | Poaceae | |
| Leptochloa panicea | mucronate sprangletop | Poaceae | |
| Leptochloa panicea ssp. brachiata | mucronate sprangeltop | Poaceae | |
| Leptochloa viscida | sticky sprangletop | Poaceae | |
| Leptosiphon | Polemoniaceae | ||
| Leptosiphon aureus | golden linanthus | Polemoniaceae | |
| Leptosiphon aureus ssp. aureus | golden linanthus | Polemoniaceae | |
| Leptosiphon aureus ssp. decorus | golden linanthus | Polemoniaceae | |
| Leptosiphon floribundum | many-flower linanthus | Polemoniaceae |