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.
