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.

This species has only recently appeared in this state, and, no doubt, in time will become an obnoxious weed at least in the southern part of the state. I first found it in 1931 in a 3-acre hogyard and it covered at least a fourth of the area. Hogs in the yard did not feed upon it. It is a native of the southern states and is introduced northward.