Slimleaf sneezeweed

Annuals, 20–80 cm. Stems usually 1, branched distally, narrowly winged, sparsely hairy proximally, moderately hairy distally. Leaves glabrous or sparsely hairy (basal withered by flowering); proximal blades lance-linear, usually coarsely or irregularly laciniate; mid and distal blades lance-linear to linear, entire. Heads 5–50(–100+) per plant, in paniculiform arrays. Peduncles 2–8 cm, sparsely to moderately hairy. Involucres globose to slightly ovoid, 6–11(–13) × 6–11(–13) mm. Phyllaries moderately hairy. Ray florets 8–9, pistillate, fertile; corollas yellow throughout or red proximally and yellow distally or red throughout, 6–12 × 3–8 mm. Disc florets 150–300(–500+); corollas yellow-green proximally, brown to purple distally, 2.5–3.2 mm, lobes 5. Cypselae 1–1.2 mm, moderately hairy; pappi of 6(–7) entire, aristate scales 2–2.5 mm. 2n = 28.

Flowering (Feb–)Mar–May(–Jul). Sandy soils, ditches, open pastures, edges of ponds and streams; 10–200 m; Tex.