Proc. Amer. Acad. Arts 25: 125. 1890.
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.
Phenology: Flowering Jun–Aug.
Habitat: Dry, open Jeffrey pine woods, gravelly serpentine grounds in forest openings
Elevation: 800-2200 m
Streptanthus barbatus is known from Siskiyou, Tehama, and Trinity counties.