Plants pilose basally, trichomes (soft), simple, to 1.5 mm, these rarely mixed with fewer, forked, stalked ones, sparsely pubescent distally. Stems ascending or decumbent, 0.3-2.5 dm. Basal leaves not seen. Cauline leaves: (proximal) petiole to 1 cm or (distal and bracts) subsessile; blade 2.5-4.5 cm (smaller distally), margins pinnatifid to pinnatisect (less divided distally); lobes 2-4 on each side, oblong to linear, 0.3-1.5 cm × 1-3 mm, shorter than terminal, margins entire. Fruiting pedicels divaricate-ascending, straight, 3-10(-28) mm, pilose. Flowers: sepals 1.2-2 × 0.7-0.9 mm, glabrous; petals (not with purple tinge), oblanceolate to spatulate, 1.6-2.5 × 0.7-0.9 mm, cuneate into short claw; filaments 1.2-1.7 mm; anthers 0.3-0.4 mm. Fruits obdeltoid, 4-5 × 4-5 mm, length equal to width; valves 2, thin-leathery proximally, thick-leathery to subwoody and tuberculate-rugose on outside distally, puberulent, trichomes simple, antrorse, these sometimes mixed with minute, 1-forked ones; septum present; ovules 4-8 per ovary; style 0.3-0.9 mm. Seeds brown, 1.2-1.5 × 0.6-0.9 mm. Flowering Mar. Subalkaline clay in scrub; of conservation concern (as Twisselmannia californica); ca. 70 m; Calif. Tropidocarpum californicum is known from adjacent parts of Kern and King counties in San Joaquin Valley.