Perennials; (caudex branched); glabrous, (sepals and leaf blade apices pubescent). Stems (sometimes ascending), unbranched or branched (few), 1.5-8(-9.2) dm. Basal leaves subrosulate (in juvenile plants); shortly petiolate; blade obovate, 1-2.7 cm (5-14 mm wide), margins dentate apically (teeth with relatively short, bristly trichomes). Cauline leaves: blade (fleshy), broadly ovate to orbicular, 0.7-3.5 cm × 5-24 mm (not smaller distally), base auriculate to amplexicaul, (proximally overlapping, distally not overlapping), margins usually entire, (apex obtuse). Racemes ebracteate, (lax in fruit). Fruiting pedicels erect to ascending, (straight), 3-8 mm. Flowers: calyx campanulate; sepals (ascending), yellowish green (in bud) or purple (in flower), (ovate), 4-7 mm, not keeled, (apex with short, bristly, flattened trichomes); petals purplish (with darker veins), 5-9 mm, blade 0.5-3 × 0.3-0.7 mm, margins slightly crisped, claw 4-7 mm, wider than blade; stamens in 3 unequal pairs; filaments (distinct): abaxial pair 4-6 mm, lateral pair 3-5 mm, adaxial pair 5-7 mm; anthers (all) fertile, 2.5-3.5 mm; gynophore 1-3 mm. Fruits erect to ascending, smooth, often strongly recurved distally, distinctly flattened, 2-7(-8.2) cm × 2-3 mm; valves each with obscure midvein (sometimes not basally, margins somewhat thickened); replum straight; ovules 16-30 per ovary; style 0.4-1 mm; stigma entire. Seeds oblong to broadly ovoid, 3-4 × 1.7-2 mm; wing (0-)0.1-0.25 mm wide at apex, (narrower at margin). 2n = 28, 56.

Flowering Jun-Aug. Dry, open Jeffrey pine woods, gravelly serpentine grounds in forest openings; 800-2200 m; Calif.

Streptanthus barbatus is known from Siskiyou, Tehama, and Trinity counties.