3. Streptanthus batrachopus J. L. Morrison, Madroño 4: 204. 1938. TYPE. United States, California, Marin Co., Mt. Tamalpais, North Side Trail, 0.5 mi NE of Rifle Camp, 8 Jun 1937, John L.. Morrison 2493 (holotype, UC!).
Herbs, annual, glabrous throughout, glaucous. Stems 0.3–1.7(–2.8) dm, erect, simple or branched near base. Basal leaves not rosulate, shortly petiolate, soon withered, obovate to oblanceolate, 0.5–2 cm, coarsely dentate, succulent, mottled; middle cauline leaves, lanceolate, 0.5–2.5 x 0.1–0.7 cm, sessile, auriculate, entire or dentate, not overlapping; upper leaves similar, reduced, entire. Racemes ebracteate, sometimes secund, lax, without a terminal cluster of sterile flowers; fruiting pedicels divaricate-ascending, 1–2.5(–4) mm. Flowers: sepals forming urceolate calyx, reddish-purple, ovate, 3–5 mm, keeled, erect, apex spreading; petals whitish with purple veins in adaxial pair, purplish in abaxial pair, 5–8 mm, not crisped; blade 2–3 x 1–1.5 mm; claw 3–4 mm; filaments in 3 pairs of unequal length; adaxial pair completely united, not recurved, 5–6 mm; abaxial pair united to about middle, 3–4 mm; lateral pair 1.5–2.5 mm; anthers of adaxial stamens sterile, 0.3–0.5 mm; anthers of abaxial and lateral stamens fertile, 1.4–1.7 mm. Fruits 1.3–3 cm x 1–1.5 mm, divaricate-ascending, slightly flattened, straight to slightly curved, slightly torulose; valves glabrous, with obscure midvein; gynophore 0.3–0.7 mm; replum straight; style 0.2–0.8 mm; stigma entire; ovules and seeds 12–22 per fruit. Seeds oblong, 1.3–2 x 0.8–1.2 mm, flattened; wing 0.1–0.3 mm wide distally, narrower at margin, rarely absent. 2n = 28.
Habitat: serpentine barrens and outcrops in chaparral.
Elevation: 100–600 m.
Distribution: United States (California/Marin Co.).