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.