Annuals; glabrous or puberulent. Stems often several from base, usually procumbent to decumbent, rarely ascending, branched distally, (0.3-)0.6-2.5(-3.5) dm. Basal leaves rosulate; petiole (1-)2-5(-5.8) cm; blade 1- or 2-pinnatisect, (3-)4-10(-15) cm, margins (of lobes) entire or dentate. Cauline leaves shortly petiolate; blade pinnatisect, base cuneate, not auriculate, margins (of lobes) entire or dentate, (similar to basal, smaller and less divided distally). Racemes (leaf-opposed), ± slightly elongated in fruit; rachis glabrous. Fruiting pedicels ascending, straight, (stout, terete), (0.7-)1-2(-2.4) × 0.4-0.5 mm, glabrous. Flowers: sepals (persistent), oblong, 1-1.5 × 0.5-0.6 mm; petals white, obovate to obovate-oblong, 1-2 × 0.4-0.6 mm, claw absent; stamens 6; filaments (median pairs) 0.7-1 mm, (glabrous); anthers 0.15-0.25 mm. Fruits (indehiscent), reniform to ovate-cordate, 2.3-3.4 × 3-4.4 mm, apically not winged, apical notch absent; valves thick, rugose-verrucose, with distinct ridges, prominently veined, glabrous; style 0.2-0.7 mm. Seeds ovate-oblong, (curved, not winged), 1.2-1.6 × 0.7-1 mm. 2n = 32. Flowering May-Aug. Waste grounds, abandoned fields, pastures, roadsides, disturbed sites; introduced; N.B., N.S., Ont., Que.; Ala., Calif., La., Mo., N.J., Tenn.; Europe; sw Asia; n Africa; introduced also in South America (Chile), s Africa, Australia.