Annuals, 8-80 cm (taproots shallow). Stems 1, erect (often reddish), stout (fistulose), simple or branched proximally, coarsely setose or hispid (at least distally, setae yellowish). Leaves basal and cauline; petiolate; blades oblan-ceolate, often runcinate or lyrate, 5-30 × 1-8 cm, margins dentate to pinnately lobed (terminal lobes often relatively large), apices acute to obtuse, faces finely hispid (coarsely setose along midribs; cauline leaves lanceolate, bases sagittate with acuminate lobes, margins dentate to deeply laciniate proximally). Heads 10-20, in paniculiform or cymiform arrays. Calyculi of 10-14, linear, coarsely setose bractlets 2-4 mm. Involucres cylindro-campanulate, 6-10 × 4-10 mm. Phyllaries 12-16, lanceolate, 6-7 mm, (bases strongly keeled and thickened, margins green to yellowish), apices acuminate, abaxial faces coarsely setose or hispid, adaxial with fine hairs. Florets 10-20; corollas yellow, sometimes reddish abaxially, 8-10 mm. Cypselae reddish brown, fusiform, 3-5 mm, beaked (beaks 1-2 mm), ribs 10 (rounded, spiculate near bases of beaks); pappi white (fine, soft), 4 mm. 2n = 8.
Flowering May-Nov. Openings in mixed conifer forest, disturbed areas, lawns; 50-500 m; introduced; Calif., Conn., Mo., Mont., N.Y., Ohio, Oreg., Pa., Tenn., Tex., Vt., Wis.; Europe.
Crepis setosa is recognized by its annual habit, shallow roots, coarsely setose stems, leaves, and involucres, the relatively large runcinate leaves, sagittate-laciniate cauline leaves, finely beaked cypselae, and white, fine pappus bristles.