Scientific Name: Cirsium ochrocentrum
Synonyms: Carduus ochrocentrus, Cnicus ochrocentrus
Common Names: Yellowspine Thistle, Yellow-spine Thistle
Duration: Biennial, Perennial
Growth Habit: Herb/Forb
Arizona Native Status: Native
Habitat: Upland, Mountain. This weedy wildflower grows along roadsides and in fields, pastures, grasslands, and woodland clearings.
Flower Color: Pink, Red, White, Pale lavender to purple
Flowering Season: Summer, Fall (early)
Height: Up to 3 feet (0.9 m) tall
Description: The broad, brushlike flower heads have numerous disk flowers, no rays, and green, yellow spine-tipped phyllaries (bracts). The leaves usually have curled-under margins and are green with a thin covering of woolly gray hair above, densely covered with white woolly hair below, alternate, deeply pinnately lobed, edged with stout, sharp, yellow spines, and oblong, narrowly elliptic, or oblanceolate in shape. The leaf lobes are tilted downwards so that they are almost perpendicular to the rest of the leaf, giving the leaves a wavy, undulating appearance. The stems are sturdy, erect to ascending, and covered in a dense mat of grayish white hair.
The very similar Wavyleaf Thistle (Cirsium undulatum) has smaller, thinner spines.
Kingdom: Plantae – Plants
Subkingdom: Tracheobionta – Vascular plants
Superdivision: Spermatophyta – Seed plants
Division: Magnoliophyta – Flowering plants
Class: Magnoliopsida – Dicotyledons
Family: Asteraceae – Aster family
Genus: Cirsium Mill. – thistle
Species: Cirsium ochrocentrum A. Gray – yellowspine thistle
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