8. Streptanthus callistus J. L. Morrison, Madroño 4: 205. 1938. TYPE: United States, California: Santa Clara Co., Arroyo Bayo, Mt. Hamilton Range, 6.8 mi ESE of Isabel Creek on road to San Antonio Valley, 2000 ft, 5 May 1935, C. W. & H. K. Sharsmith 3074 (holotype, UC!; isotype, GH!).
Herbs, annual, hirsute, somewhat glaucous. Stems 2–9 cm, simple or branched, bristly especially below. Basal leaves not rosulate, short petiolate, soon withered, oblong-orbicular to obovate, 0.7–1.5 cm, dentate; middle cauline leaves broadly ovate to obovate, 0.8–1.7 x 0.4–1.3 cm, sessile, amplexicaul, hirsute, dentate; upper leaves similar, reduced. Racemes ebracteate, not secund, with a terminal cluster of sterile flowers; fruiting pedicels divaricate, 2–3 mm, hirsute. Flowers: sepals forming narrowly campanulate calyx, green to purplish, narrowly ovate, 3–5 mm, keeled and saccate basally, sparsely hirsute; sterile sepals lilac-purple, linear-lanceolate, not keeled, 8–13 mm, glabrous; petals 8–11 mm, purple with darker purple veins; blade flaring, 4–6 x 2.5–3.5 mm; claw 4–5 mm, narrower than blade; filaments in 3 pairs of unequal length, purple; adaxial pair united nearly to apex, 5–6.5 mm; abaxial pair united, 4–5 mm; lateral pair 2–3 mm; anthers of adaxial stamens sterile, 0.4–0.8 mm; anthers of abaxial and lateral stamens fertile, 1.4–1.8 mm. Fruits 1.3–2.5 cm x 2.5–3.5 mm, divaricate, slightly flattened, curved upwards; valves hispid with setose trichomes 0.5–0.8 mm, with a prominent midvein; gynophore 0.1–0.3 mm; replum straight; style 0.2–0.5 mm; stigma slightly 2-lobed; ovules and seeds 46–60 per fruit. Seeds ovoid, 1.2–1.5 x 0.6–0.8 mm, plump; wing absent. 2n = 28.
Habitat: gravelly sedimentary scree and lag-barrens in chaparral-oak woodlands.
Elevation: 500–900 m.
Distribution: United States (California/Santa Clara Co.).