Biennials. Trichomes of leaves 2- or 3-rayed. Stems erect, unbranched or branched distally, (0.6–)1.2–6.5(–8) dm. Basal leaves (often withered by fruiting); blade oblanceolate, 2–10 cm × (0.2–)0.5–1.5(–2.4) mm, base attenuate, margins dentate, apex acute. Cauline leaves (distal) sessile; blade margins entire or denticulate. Racemes considerably elongated in fruit. Fruiting pedicels horizontal to divaricate, slender, narrower than fruit, 5–16(–25) mm. Flowers: sepals oblong to linear-oblong, 8–12 mm, lateral pair slightly saccate basally; petals yellow, obovate to suborbicular, 13–22 × 4–9 mm, claw 8–15 mm, apex rounded; median filaments 8–14 mm; anthers linear, 2.5–4 mm. Fruits widely spreading or divaricate, narrowly linear, usually straight, rarely curved upward, not torulose, (3–)5–12(–14) cm × 1.2–2.7 mm, 4-angled, strongly (longitudinally) 4-striped; valves with prominent midvein and replum, densely pubescent outside, trichomes 2-rayed between midvein and replum, glabrous inside; ovules 72–120 per ovary; style cylindrical, slender, 1–4 mm, sparsely pubescent; stigma slightly 2-lobed, lobes as long as wide. Seeds ovoid, (1–)1.3–2.3 × 0.7–1.2 mm; usually not winged, rarely winged distally. 2n = 36.
Phenology: Flowering Apr–Jun(-Aug).
Habitat: Prairies, sand dunes, roadsides, bluffs, sandhills along stream banks, knolls, open plains
Elevation: 200-2000 m
Alta., Man., Sask., Ark., Colo., Ill., Kans., Minn., Mont., Nebr., N.Mex., N.Dak., Okla., S.Dak., Tex., Wyo.