Annuals; glabrous or sparsely pubescent. Stems erect, branched proximally and distally, (1-)2-6(-7.5) dm, glabrous or sparsely pubescent at least basally. Basal leaves not rosulate; petiole (0.5-)1-4.5(-6) cm; blade oblanceolate or oblong (in outline), (1.5-)3-12 (-15) cm × (5-)10-60(-90) mm, margins runcinate to pinnatisect; lobes (1-)2-6(-8) on each side, oblong or lanceolate, smaller than terminal lobe, margins entire, dentate, or lobed. Cauline leaves similar to basal; (distalmost) blade (smaller, to 2 cm wide), margins entire or 1-3-lobed. Fruiting pedicels divaricate or ascending, slender, much narrower than fruit, (5-)7-12(-20) mm. Flowers: sepals erect, oblong, 2-2.5 × 1-1.5 mm; petals oblong-oblanceolate, 2.5-3.5(-4) × 1-1.5 mm, claw 1-1.5 mm; filaments 2.5-4 mm; anthers ovate, 0.5-0.9 mm. Fruits (divaricate to ascending, young fruits overtopping flowers), narrowly linear, straight or slightly curved inward, slightly torulose, slender, (2.5-)3-4(-5) cm × 0.9-1.1 mm; valves glabrous; ovules 40-90 per ovary; style 0.2-0.5 mm; stigma prominently 2-lobed. Seeds 0.8-1 × 0.5-0.6 mm. 2n = 14.

Flowering Dec-May. Rocky slopes, orchards, roadsides, fields, pastures, waste grounds, prairies, disturbed sites; 0-1700 m; introduced; Ariz., Calif., Colo., Conn., Fla., Idaho, Mass., Mich., Nev., N.Mex., Ohio, Pa., Tex., Utah, Wyo.; Europe; w, c Asia; n Africa; introduced also in South America, Australia.