10. Caulanthus hallii Payson, Ann. Missouri Bot. Gard. 9: 290. 1923; Streptanthus hallii (Payson) Jepson, Fl. Calif. 2: 23. 1936. TYPE: United States, California, Coyote Canon, El toro Mt., San Jacinto Mountains, 5000 ft, 25 May 1899, H. M. Hall 1165 (holotype, MO; isotypes, 2UC!).

Herbs, annual, sparsely to densely hispid with simple trichomes, glaucous. Stems 2–12 dm, erect or ascending, simple or branched above, hollow, sometimes only slightly inflated. Basal leaves rosulate; petiole 0.5–3.5 cm; blade oblanceolate to oblong in outline, 1.5–11.5 x 0.5–5.5 cm, hispid, margin pinnately lobed, lobes dentate; uppermost cauline leaves sessile, lanceolate-linear, sparsely hispid, entire. Racemes without a terminal cluster of sterile flowers, ebracteate, somewhat lax, elongated in fruit; fruiting pedicels ascending, 9–25 mm, hispid or subglabrous. Sepals creamy white, lanceolate to ovate, 3–6.5 ´ 1.8–2.5 mm, erect, equal, not keeled; petals creamy white, 6–10.5 mm; blade 3–4 ×1.5–2 mm, not crisped; claw narrowly oblanceolate or oblong, 3–6 x 2–3 mm; filaments in 3 pairs of unequal length, free, adaxial pair 4.5–8 mm, abaxial pair 2.5–6 mm, lateral pair 1.5–4.5; anthers narrowly oblong, 2–3 mm, adaxial pair slightly shorter; ovules 78–96 per ovary. Fruits 6.5–12.5 cm ´ 1.8–2.2 mm, divaricate to ascending, terete, sometimes curved; valves with a prominent midvein; style to 2 mm; stigma slightly 2-lobed. Seeds 1–1.6 x 0.7–1 mm; cotyledons entire.

Flowering: Mar–May.

Habitat: rocky areas, chaparral, scrub.

Elevation: 300–1800 m.

Distribution: United States (California/Riverside and San Diego counties).