Annuals; densely hirsute-hispid throughout, (trichomes to 1.4 mm). Stems unbranched or branched basally, 0.3-3 dm. Basal leaves not rosulate; shortly petiolate; blade obovate, 1-5 cm, margins coarsely to shallowly dentate. Cauline leaves: blade obovate to oblong, 0.7-6 cm × 2-25 mm, base cuneate or truncate, not auriculate or (distally) minutely ariculate, margins coarsely dentate. Racemes ebracteate, (not secund, with a terminal cluster of sterile flowers). Fruiting pedicels divaricate-ascending, (straight), 2-5 mm. Flowers: calyx subcampanulate; sepals pale green to purplish, ovate, 4-6 mm, not keeled; petals light purple (with white margins), 6-9 mm, blade 2-3 × 1-1.5 mm, margins crisped, claw 5-6 mm, wider than blade; stamens in 3 unequal pairs; filaments: abaxial pair (connate ca. 1/2 their length), 4-5 mm, lateral pair 3-4 mm, adaxial pair (exserted, connate to near apex), 5-6 mm; anthers: abaxial and adaxial pairs fertile, 1.5-1.8 mm, adaxial pair sterile, 0.3-0.5 mm; gynophore 0.1-0.3 mm. Fruits divaricate-ascending to suberect, straight, flattened, 4-8.5 cm × 2-2.5 mm; valves each with prominent midvein; replum straight; ovules 34-66 per ovary; style 0.4-1 mm; stigma slightly 2-lobed. Seeds ovoid to suborbicular, 1.6-2 × 1.2-1.8 mm; wing 0.2-0.35 mm wide, continuous. 2n = 28.

Flowering Mar-Jun. Talus or rocky outcrops (Franciscan formation, largely on chert) and sparsely vegetated openings in grassland or chaparral; of conservation concern; 600-1200 m; Calif.

Streptanthus hispidus is known from Mt. Diablo in Contra Costa County.