Plants (20–)30–100(–120) cm. Leaves: proximal blades usually entire, rarely serrate; mid and distal leaves entire. Heads 20–100(–200+). Peduncles 2–5(–7) cm. Involucres 5–8 × 5–8 mm. Ray florets 10–14; corollas 5.5–11.5 × 2.7–5.2 mm. Disc florets 150–300(–500+). Cypselae 0.6–0.9 mm; pappi 0.05–0.2 mm. 2n = 26.

Flowering (May–)Jun–Aug (sometimes again in fall). Calcareous soils, ditches, washes, along streams; 100–600 m; Ark., Okla., Tex.