Annuals; (often glaucous), usually glabrous, rarely sparsely pilose. Stems simple from base, erect, branched distally, (1-)2-8 (-10) dm. Basal leaves (withered by anthesis); not rosulate; petiole 1-4 cm; blade 1- or 2-pinnatifid or pinnatisect (lobes ovate to oblong), 2-8(-10) cm, margins (of lobes) entire or dentate. Cauline leaves petiolate; blade similar to basal, usually less divided, rarely undivided, (distal) often linear, bases not auriculate, margins entire. Racemes considerably elongated in fruit; rachis glabrous. Fruiting pedicels suberect to ascending, appressed to rachis, straight, (terete or slightly flattened), 1.5-4(-6) × 0.4-0.6 mm, glabrous. Flowers: sepals oblong-obovate, 1-1.8 × 0.5-0.8 mm; petals white or lavender, spatulate to obovate, 2-3.5(-4) × 0.7-1.4 mm, claw 1-1.4 mm; stamens 6; filaments (median pairs) 1.5-2 mm, (glabrous); anthers 0.4-0.5 mm. Fruits broadly ovate or ovate-oblong, (4-)5-6.4(-7) × 3-4.5 (-5.6) mm, apically broadly winged, apical notch 0.2 0.8 mm deep; valves thin, smooth, not veined, glabrous; style 0.1-0.5(-0.8) mm, usually included in, rarely subequaling, apical notch. Seeds (reddish brown), ovate-oblong, 2-2.7(-3) × 1-1.5 mm, (3-lobed). 2n = 16, 32.

Flowering Apr-Aug. Gardens, old fields, vacant lots, disturbed areas, railroad embankments, waste grounds, roadsides, cultivated areas; introduced; Alta., B.C., Man., Nfld. and Labr. (Nfld.), N.W.T., N.S., Ont., P.E.I., Que., Sask.; Conn., Idaho, Iowa, Maine, Md., Mass., Mich., N.H., N.Y., Ohio, Oreg., Pa., R.I., Tenn., Wash., Wyo.; Europe; sw Asia; perhaps ne Africa; introduced also in South America (Argentina), Australia.

Lepidium sativum is cultivated as a salad green and is sporadically naturalized, though never as an aggressive weed. It is seldom collected; the above range may be incomplete.