Plants (10–)20–60(–100) cm. Leaves: basal and proximal cauline usually withered by flowering; basal blades linear to ovate, usually entire or pinnately toothed sometimes pinnatifid; proximal blades usually linear, usually entire, sometimes pinnately toothed. Ray corollas 6.5–14 × 4–10 mm. Disc florets 75–150+; corollas yellow to yellow-brown distally, 2–2.7 mm. Cypselae 0.9–1.3 mm; pappi of 6–8 scales 1.2–1.8 mm. 2n = 30.

Flowering (Feb–)Jul–Oct(–Dec). Roadsides and fields; 20–400 m; Ala., Ark., Calif., D.C., Fla., Ga., Ind., Kans., La., Mich., Miss., Mo., N.C., Okla., Pa., S.C., Tenn., Tex., Va.

Variety amarum is introduced in California.