Smallhead sneezeweed

Annuals, 25–120 cm. Stems 1(2–10), branched distally, moderately to strongly winged, glabrous or sparsely hairy. Leaves glabrous or sparsely to moderately hairy (basal withered by flowering); proximal and mid blades narrowly elliptic to narrowly oblong-elliptic, usually serrate to undulate-serrate, sometimes deeply toothed or laciniate; distal blades narrowly elliptic to narrowly oblong-elliptic, serrate to undulate-serrate. Heads 20–300+ per plant, in paniculiform arrays. Peduncles 1.8–8 cm, moderately hairy. Involucres globoid to usually ovoid, 4–12 × 4–12 mm. Phyllaries (connate proximally) moderately hairy. Ray florets 7–13, pistillate, fertile; corollas usually yellow throughout, sometimes reddish proximally and yellow distally, 2.6–9.1 × 1.5–6.7 mm. Disc florets 120–400+; corollas yellow to yellow-green proximally, brown to reddish brown distally, 1.2–2.4 mm, lobes (4–)5. Cypselae 0.7–1.4 mm, moderately hairy; pappi of usually 6 entire, non-aristate scales (0.2–)0.3–0.7 mm.

Varieties 2 (2 in the flora): sw, sc United States, n Mexico.