Plants annual, 15–100+ cm.
Stems usually glabrous.
Leaves linear to narrowly lanceolate, 5–15+ × 1–7 cm, reduced below inflorescences, bases with 2 downward-pointing basal lobes clasping stems, margins entire or denticulate or with a few sharp, linear lobes, surfaces glabrous; sessile.
Inflorescences 10–30+ heads in panicle- or raceme-like arrays; peduncles short.
Involucres 6–13 mm.
Phyllaries inner, lance-linear, surfaces glabrous; outer deltate to lance-linear, gradually shorter.
Florets 6–12(20+); ligules 8–12 mm, yellow, sometimes bluish-tinged.
Fruits bodies broadly elliptic, 2.5–3.5 mm, brown, each face 5–7-veined, minutely roughened; beaks slender, (2)5–6 mm; pappus bristles persistent or deciduous, white.
2n=18.
Openings in woods, fields, roadsides, disturbed areas. Flowering Jul–Sep. 0–800 m. Casc, Lava, Sisk, WV. CA, NV, WA; throughout eastern and southern North America; Europe. Exotic.
as described under Lactuca saligna
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.