Wright’s snakeweed

Xanthocephalum wrightii (A. Gray) A. Gray

Annuals, 30–200 cm. Stems glabrous. Leaves: proximal usually persistent at flowering, cauline blades obscurely (1-), 3-, or 5-nerved, mostly narrowly elliptic-lanceolate, 40–70 × 2–4 mm, reduced distally. Heads usually in open arrays. Involucres campanulate, 4.5–7.5 mm diam. Phyllary apices conduplicate, swollen (appearing abaxially keeled). Ray florets 8–19; corollas yellow, 5–12 mm. Disc florets (30–)40–60. Cypselae 0.7–2 mm, faces (pebbly or warty with raised, blisterlike oil cavities) glabrous; pappi coroniform, 0.1–0.2 mm (margins entire or obscurely denticulate or erose). 2n = 8.

Flowering Jul–Oct(–Nov). Meadows and clearings in pine, pine-oak, and pine-fir woods, ditches, road cuts, alluvium; 1800–2800 m; Ariz., N.Mex.; Mexico (Chihuahua, Sinaloa, Sonora).