Annuals or biennials, 10-140(-200) cm. Stem bases soft to hard, herbaceous, often hollow. Leaves: blades of mid cauline spatulate or oblong to obovate or lanceolate, 6-35 × 1-15 cm, bases auriculate, auricles deltate to lanceolate, ± straight, acute, margins usually pinnately (often runcinately) lobed, lobes ± deltate to lanceolate, not constricted at bases, terminals usually larger than laterals, entire or dentate. Peduncles usually glabrous, sometimes stipi-tate-glandular. Involucres 9-13+ mm. Phyllaries usually glabrous, sometimes tomentose and/or stipitate-glandular. Corollas: ligules ± equaling tubes. Cypselae dark brown, mostly oblanceoloid, 2.5-3.5+ mm, ribs 2-4 on each face, faces transversely rugulose or tuberculate across and between ribs; pappi 5-8 mm. 2n = 32, 36. Flowering (Apr-)Jul-Oct (year-round in south). Disturbed sites, gardens, roadsides, along streams; 0-2000 m; introduced; Greenland; St. Pierre and Miquelon; Alta., B.C., Man., N.B., Nfld. and Labr. (Nfld.), N.W.T., N.S., Ont., P.E.I., Que., Sask.; Ala., Alaska, Ariz., Ark., Calif., Colo., Conn., Del., D.C., Fla., Ga., Idaho, Ill., Ind., Iowa, Kansas, Ky., La., Maine, Md., Mass., Mich., Minn., Miss., Mo., Mont., Nebr., Nev., N.H., N.J., N.Mex., N.Y., N.Dak., Ohio, Okla., Oreg., Pa., R.I., S.C., S.Dak., Tenn., Tex., Utah, Vt., Va., Wash., W.Va., Wis., Wyo.; Europe; introduced also in Mexico, West Indies, Bahamas, Central America, South America, Africa, Asia, Pacific Islands (New Zealand), Australia.

Plant: Annual forb usually <1 m; herbage with milky sap; plants not spiny; stems often branched from below middle Leaves: alternate; basal generally < cauline, generally tapered or abruptly wing-petioled; cauline 5-35 cm, upper sessile, clasping, often widest at base, basal clasping lobes acute, not curled or coiled; blades nearly all lobed except in dwarfed plants, lobes variable in width, terminal lobe often widely arrowhead-shaped INFLORESCENCE: primary inflorescence a head, each resembling a flower; heads ligulate, in cymes; peduncles 0.5-7 cm, glabrous to bristly-glandular, sometimes cottony-tomentose just below heads; involucre 10-13 mm; phyllaries generally in 3 series, outer many, short-triangular, those of inner 2 series linear, tapered; receptacle ± flat, naked Flowers: many, ligule ± = tube, yellow, readily withering Fruit: achenes, 2.5-3.8 mm, flat, 2-4-ribbed, cross-wrinkled on each face; pappus bristles fine, white, ± 2 X fruit Misc: Weed in waste places, gardens, etc; < 1500 m.; Most of year References: J.C. Hickman, ed. The Jepson Manual.W.B. McDougal. Seed plants of Northern Arizona. ASU specimens.