Plants 30–120 cm. Leaves: proximal and mid blades serrate to undulate-serrate, glabrous or sparsely hairy; distal blades glabrous or sparsely hairy. Heads 20–150(–300+) per plant. Peduncles 1–3.5 cm, projecting terminal heads barely beyond foliage. Involucres 4–8 × 4–8 mm. Ray florets 7–13; corollas yellow, 2.6–4.8 × 1.6–3.9 mm. Disc florets 120–300+; corollas 1.2–1.6 mm, lobes (4–)5. Pappi (0.2–)0.3–0.4(–0.5) mm. 2n = 26.

Flowering (Feb–)Jun–Jul(–Nov). Sandy or clay soils, ditches, washes, around ponds and lakes, along streams; 0–1500 m; Ariz., N.Mex., Okla., Tex.; Mexico (Coahuila, Nuevo León, and Tamaulipas).