Annuals (perhaps persisting), 15-70(-100+) cm. Leaves on proximal ¹/2-³/4+ of each stem; blades of undivided cauline leaves ± linear to filiform, margins entire or denticulate, midribs usually prickly-setose. Heads in race-miform to spiciform arrays. Involucres 6-9(-13+) mm. Phyl-laries usually erect in fruit. Florets 6-12(-20+); corollas yellow (sometimes abaxially bluish), usually deliquescent. Cypselae: bodies pale brown, ± flattened, elliptic to oblanceolate, 2.5-3.5 mm, beaks ± filiform, (2-)5-6 mm, faces 5-7-nerved; pappi white, 5-6 mm. 2n = 18. Flowering Aug-Oct. Disturbed sites; 10-1500 m; introduced; Ont., Que.; Ala., Ariz., Ark., Calif., Del., D.C., Ga., Ill., Ind., Iowa, Kans., Ky., La., Maine, Md., Mass., Mich., Mo., Nebr., Nev., N.J., N.Mex., N.Y., N.C., Ohio, Okla., Oreg., Pa., S.C., Tenn., Tex., Va., Wash., W.Va., Wis.; Europe; introduced also in Mexico.

Plant: Annual from taproot, 0.5-1(2) m, sap milky; stems decumbent or erect below, glabrous or bristly below Leaves: basal and cauline, alternate, few-many, linear to lanceolate, entire or with linear lobes, clasping, glabrous or prickly-bristly on midvein INFLORESCENCE: primary inflorescence a head, each resembling a flower; heads ligulate, many, in panicles, narrow, spike-like; branches and peduncles often appressed; heads in flower 4-5 cm wide; involucre in fruit 10-17 mm Flowers: 8-12; corolla pale yellow; ligules yellow or cream to blue, readily withering Fruit: 7-9 mm (including beak), brown, dark-mottled, rough, glabrous, several-veined on each face, unwinged; beak = or > body; pappus ± 6 mm, white, of many bristles, falling separately Misc: Waste, mostly urban places; < 750 m.