Annuals; hispid. Stems erect, usually branched distally, 1-7 dm. Basal leaves rosulate; petiole 0.2-1 cm; blade oblanceolate, 1-7 cm × 4-18 mm, margins coarsely dentate or pinnately lobed. Cauline leaves (median) sessile; blade ovate to oblong, 2-8 cm × 5-20 mm, (smaller distally, base amplexicaul to sagittate), margins coarsely dentate or entire. Racemes (densely flowered), without a terminal cluster of sterile flowers. Fruiting pedicels reflexed, 2-5 mm. Flowers: sepals erect, (yellow), lanceolate, 3-6.5 × 1.5-2 mm (equal, keeled); petals creamy white or pale yellow (sometimes with purple midvein), 10-14 mm, blade 4-5 × 1.5-2 mm, not crisped, claw oblanceolate or oblong, 5-9 × 1-1.7 mm; filaments tetradynamous, median pairs 3-5 mm, lateral pair 2-4 mm; anthers oblong, equal, 1-3 mm. Fruits usually reflexed, rarely divaricate (often straight), terete, 3-7.5 cm × 1.2-1.5 mm; valves each with obscure midvein; ovules 48-62 per ovary; style 0-3 mm; stigma 2-lobed. Seeds 1-2 × 0.9-1.1 mm. 2n = 28. Flowering Mar-Jun. Chaparral, scrub, pinyon-juniper woodlands; 400-2100 m; Calif. Caulanthus simulans is restricted to Riverside and San Diego counties.