Perennials; glabrous (or petioles and sepals pubescent). Stems erect or ascending, unbranched or branched distally, (hollow, sometimes slightly inflated), 2-10 dm. Basal leaves rosulate; petiole 0.5-9 cm; blade obovate to oblanceolate or elliptic (in outline), 1-14 cm × 5-25 mm, margins entire, dentate-sinuate, lyrate, or pinnatifid-runcinate. Cauline leaves (distalmost) shortly petiolate; blade linear to narrowly oblanceolate, margins entire. Racemes (densely flowered), without a terminal cluster of sterile flowers. Fruiting pedicels ascending, 1-6 mm. Flowers: sepals erect, (creamy white or purple), ovate to lanceolate, 6.5-9.5 × 2.7-4 mm, (equal, pubescent); petals purple, 11-17 mm, blade 4-7 × 1-1.7 mm, not or hardly crisped, claw oblanceolate, 7-13 × 2.5-3.5 mm; filaments tetradynamous, median pairs 5-7 mm, lateral pair 4-6 mm; anthers narrowly oblong, equal, 4-6 mm. Fruits erect to ascending, terete or slightly latiseptate, 4.5-12 cm × 2.2-2.8 mm; valves each with obscure midvein; ovules 46-58 per ovary; style obsolete or, rarely, to 0.4 mm; stigma slightly 2-lobed (lobes opposite valves). Seeds 2-3.5 × 1.3-1.8 mm. 2n = 28.
Flowering May-Aug. Margin of montane forests, sagebrush, pinyon-juniper woodland; 1500-3200 m; Calif., Nev., Oreg., Utah.
Caulanthus major is found in eastern and southern California, Nevada, southeastern Oregon, and Utah.