Annuals; sparsely to densely pubescent or glabrous. Stems (simple from base), unbranched or branched distally, 1.5–8.5(–11) dm, (sparsely to densely hirsute basally, usually glabrous distally, rarely throughout). Basal leaves (withered by flowering); not rosulate; petiolate; blade similar to cauline. Cauline leaves: blade ovate to oblong or lanceolate, 1–9 cm × 5–30 mm, (smaller distally), base amplexicaul, margins usually entire, rarely shallowly dentate, (midvein abaxially glabrous or pubescent, surfaces glabrous distally). Racemes ebracteate, (dense to lax). Fruiting pedicels divaricate-ascending, (straight), 5–16 mm, (glabrous or pubescent). Flowers: calyx campanulate; sepals purplish, 4–7 mm, not keeled, (hirsute, trichomes 0.7–2 mm, both pairs with subapical callosities, 1–2.5 mm); petals purple (with dark purple center), 9–17(–20) mm, blade 5–10 × 5–7 mm, margins not crisped, claw 4–7 mm, narrower than blade; stamens tetradynamous; filaments: median pairs (distinct), 5–6 mm, lateral pair 3–4 mm; anthers (all) fertile, 1.5–2.8 mm; gynophore 1–1.5 mm. Fruits ascending to suberect, smooth, straight, flattened, 0.6–1.4 cm × 2–3 mm; valves each with prominent midvein; replum straight; ovules 54–86 per ovary; style 1–1.5 mm; stigma strongly 2-lobed. Seeds broadly oblong, 2–2.7 × 1–1.2 mm; wing 0.1–0.25 mm wide, continuous.