Annuals. Stems few to several from base, erect, branched distally, (0.7-)1-6(-7) dm. Basal leaves: petiole (0.5-)1-4(-5) cm; blade lanceolate, oblanceolate, or ovate, (1.2-)2-5(-6) cm × (5-)10-20 (-30) mm, base cuneate, margins usually dentate, sinuate, rarely pinnatifid. Cauline leaves (distal) shortly petiolate or sessile; blade ovate, lanceolate, or oblong, 1-4(-5) cm × (3-)10-20(-30) mm, base cuneate, margins entire, dentate, or repand. Racemes considerably elongated in fruit. Fruiting pedicels 1.5-2.5 mm. Flowers: sepals purple to lavender, linear, (6-)7-9(-10) × 0.8-1.2 mm; petals white to pale lavender, (10-)12-15 × (1.5-)2-3 mm; filaments 6-7 mm; anthers 1.5-2(-2.5) mm. Fruits: valves transversely ovate to suborbicular, 3.5-5 (-6) × 4-6(-7) mm, base and apex rounded, pubescent, trichomes clavate, simple, papillate (branched trichomes rarely present on fruit margin); style 0.1-0.5(-1) mm. Seeds 3-4 × 1.5-2.5 mm. 2n = 20.

Flowering (depending on elevation) Mar-Oct. Sandy deserts, sand dunes; 50-1400 m; Ariz., Calif., Nev.; Mexico (Baja California, Sonora).

Dithyrea californica is known in Arizona from Maricopa, Mohave, and Yuma counties and in Nevada from Clark and Lincoln counties. In material with immature fruits and lacking the proximal portion of stems, the species is readily distinguished from D. maritima by the presence of clavate trichomes, quite visible even on the ovaries of developing fruits. By contrast, D. maritima has branched instead of clavate trichomes.

Al-Shehbaz 2014 (Jepson Online)

Duration: Annual Nativity: Native Lifeform: Forb/Herb General: Habit: Plant densely hairy. Stem: several from base, branched distally, (0.7)1--6(7) dm. Leaves: Leaf: basal 2--11 cm, oblanceolate to widely ovate, dentate to shallowly lobed; cauline similar, smaller, entire to dentate Flowers: Flower: sepals (6)7--9(10) mm; petals (1)1.2--1.5 cm, (1.5)2--3 mm wide, white to pale lavender. Fruits: Fruit: style 0.1--0.5(1) mm; pedicel spreading, 1.5--2.5 mm. Seed: 2, 3--4 mm, oblong. Ecology: Found in sandy places, washes, scrub, below 4,500 ft (1372 m); flowers March-May Distribution: California, Nevada, western Arizona, northwestern Mexico. Editor: Hazelton pasted from Jepson; no edits