Perennials (may flower first year). Leaves ± scattered over proximal 3/4+ of plant height, internodes mostly 30-75+ mm; lobes mostly filiform to linear, sometimes lanceolate, (5-)15-35+ × 0.5-1(-3+) mm. Ray laminae pale yellow (fading to white), 2-4.5(-6+) mm. Disc corollas 3-4.5 mm. Cypselae 2-3(-5) mm; pappi 0, or 0.5-1 mm. 2n = 24.
Flowering year round, following rains. Open sites, along streams, rocky canyons; 100-1500 m; Ariz.; Mexico (Chihuahua, Sinaloa, Sonora).
E. B. Smith (1989) treated plants of Coreocarpus arizonicus from the flora area and Mexico as var. arizonicus and other plants of the species from Mexico as var. pubescens (B. L. Robinson & Fernald) S. F. Blake.
FNA 2006, Kearney and Peebles 1969
Duration: Perennial Nativity: Native Lifeform: Subshrub General: Herbaceous to suffrutescent perennials, flowering in the first year, 20-70 cm tall; stem solitary but much branched throughout, the growth form erect or sprawling. Leaves: Opposite, obscurely petiolate; blades pinnately divided into 3-5 linear lobes, the lobes 15-35 mm long. Flowers: Flower heads radiate, clustered in terminal panicles; calyculi (extra set of bracts below the involucre) of 1-3 linear to subulate bractlets, these much smaller than the phyllaries and sometimes absent; involucre (ring of bracts wrapped around flower head) campanulate to turbinate, 3-5 mm in diameter, the bracts (phyllaries) 5-8, unequal in 2 series, ovate to oblong; ray florets 5-8, the laminae (ray petals) pale yellow and fading to white, 2-6 mm long; disc florets 12-30, the corollas yellow with red-brown nerves, 3-5 mm high. Fruits: Achenes 2-3 mm long, oblong, strongly dorsal-ventrally compressed, with 2 pectinately divided wings; pappus none, or of 1-2 retrorsely spinulose awns, these less than 1 mm long. Ecology: Found in rich soil along streams, in open areas, and in canyons, from 3,000-5,000 ft (914-1524 m); flowers January-October. Distribution: s AZ; south to n MEX (Chihuahua, Sinaloa, Sonora). Notes: Look for this species along streams and on north-facing slopes near Tucson and farther south. The small yellow flower heads are distinctive due to them having only a few, wide, overlapping phyllaries. Note also the opposite leaves pinnately divided into narrow lobes and clustered near the bottom of the plant; and the flattened seeds which have winged margins and are sometimes topped with 1-2 awns. Ethnobotany: Unknown Etymology: Coreocarpus is from the Greek koreos, bug, and karpos, fruit, alluding to pectinately winged achenes; arizonicus refers to Arizona. Synonyms: Leptosyne arizonica Editor: LCrumbacher 2011, AHazelton 2015