Annuals; usually hispid, rarely glabrous distally, (trichomes simple, stalked, or 2-rayed forked). Stems erect, usually branched distally, 1-16(-25) dm, sparsely hispid basally. Basal leaves rosulate; petiole 0.3-5 cm; blade narrowly oblong to oblanceolate, 0.7-12 cm × 4-25 mm, margins pinnatifid to coarsely dentate-sinuate, (surfaces pubescent, trichomes simple and 2-rayed forked). Cauline leaves (median) sessile; blade lanceolate to linear-lanceolate, 1-18(-26) cm × 3-35(-45) mm (smaller distally, base amplexicaul), margins dentate or entire, (surfaces glabrous). Racemes (densely flowered), with a terminal cluster of sterile flowers. Fruiting pedicels reflexed or, rarely, spreading, 3-16 mm, usually pubescent, rarely glabrous. Flowers: sepals erect to ascending, (dark purple in bud becoming yellowish green with purplish or brown margins), ovate to narrowly lanceolate, 5-15(-19) × 2-4.5 mm (subequal, keeled, glabrous or pubescent, trichomes simple and forked); petals white or purplish (with dark purple veins), 8-25(-30) mm, blade 4-10 × 1.5-4 mm, crisped, claw oblanceolate, 4-12 × 2-2.5 mm; filaments in 3 unequal pairs, abaxial pair 3.5-8.5 mm, lateral pair 1.5-7 mm, adaxial pair (connate), 5.5-11 mm; anthers oblong to linear-oblong, unequal, 1-5 mm, (adaxial pair smaller). Fruits usually reflexed, rarely divaricate (often straight), terete or slightly latiseptate, 3.5-15 cm × 2.2-3.5 mm; valves each with prominent midvein basally; ovules 70-96 per ovary; style 0-4 mm; stigma strongly 2-lobed (lobes 0.5-1.5 mm, opposite valves). Seeds 1.5-3.5 × 1.5-2.2 mm, (cotyledons deeply 3-fid). 2n = 28.

Flowering Mar-Jun(-Jul). Grasslands, scrub, woodlands, chaparral; 100-2100 m; Calif.

Caulanthus coulteri is highly variable in almost every morphological character. For a discussion of its limits, see 14. Caulanthus lemmonii. It is known from central and southern California.