Scientific Name: Almutaster pauciflorus
Synonyms: Aster hydrophilus, Aster pauciflorus
Common Names: Alkali Marsh Aster, Marsh Alkali Aster, Alkaline Aster, Few-flower Aster, Few-flowered Aster
Growth Habit: Herb/Forb
Arizona Native Status: Native
Habitat: Riparian. This wildflower grows in damp, alkaline or saline soil along streams, in drainage areas, and in wetlands from the deserts up to moderate elevations in the mountains.
Flower Color: Pale purple, White
Flowering Season: Summer, Fall
Height: Up to 4 feet (1.2 m) tall, but usually half that
Description: The small flower heads have 15 to 30 pale purple or white rays, yellow disks, and green with translucent margins, glandular, point-tipped, appressed phyllaries (bracts at the base of the flower heads) in 3 to 4 series. The flowers are followed by bristly, rounded, tan-colored seed heads. The grasslike leaves are green, semi-fleshy, alternate, clasping, up to 4 inches (10 cm) long, tipped with a small point, untoothed, and hairless except for sometimes minutely hairy or glandular margins. The upper leaves are smaller and narrowly linear in shape, while the larger and longer lower leaves are linear to narrowly lance-shaped. The stems are green, ascending to erect, usually hairless and sometimes reddish near the base of the plant, and glandular and branched near the top. The plants are somewhat colonial and grow from long, slender underground rhizomes.
The very similar Arida riparia (Machaeranthera riparia) has much shorter leaves, flower phyllaries without translucent margins, and seeds with white pappi (bristles). Arida arizonica (Machaeranthera arida) has pinnatifid or coarsely toothed leaves. Dieteria canescens (Machaeranthera canescens) has green-tipped, non-glandular flower phyllaries. Psilactis gentryi has lance-shaped to egg-shaped leaves with either clasping, heart-shaped leaf bases or a pair of basal lobes. Arida parviflora (Machaeranthera parviflora), Machaeranthera tagetina, and Machaeranthera tanacetifolia have pinnatifid leaves. Dieteria asteroides (Machaeranthera asteroides), Dieteria bigelovii (Machaeranthera bigelovii), and Psilactis asteroides have spreading to reflexed flower phyllaries.
Butterfly Plant – The flowers attract butterflies.
Kingdom: Plantae – Plants
Subkingdom: Tracheobionta – Vascular plants
Superdivision: Spermatophyta – Seed plants
Division: Magnoliophyta – Flowering plants
Class: Magnoliopsida – Dicotyledons
Family: Asteraceae – Aster family
Genus: Almutaster A. Löve & D. Löve – alkali marsh aster
Species: Almutaster pauciflorus (Nutt.) A. Löve & D. Löve – alkali marsh aster
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