Draba quadricostata Rollins, Contr. Dudley Herb. 3: 366. 1946

Plants subscapose; puberulent, trichomes crisped, branched, mixed with setiform ones. Stems 0.2-0.6 dm, pubescent. Basal leaves thin; blade linear to oblong, 0.2-0.5 cm × 0.5-1(-1.5) mm, margins ciliate, (trichomes setiform, to 0.8 mm), apex acute, often apiculate, surfaces densely puberulent, trichomes minute, crisped, subdendritic, mixed with fewer setiform and simple ones; midvein obscure. Cauline leaves 1-5 (as bracts). Racemes 5-17-flowered, (bracteate basally). Fruiting pedicels 2-5 mm, glabrous or puberulent. Flowers: sepals 2.5-4 × 1-1.5 mm; petals pale yellow, spatulate or oblanceolate, 3-4.5 × 1.5-2 mm, attenuate to clawlike base to 1 mm; filaments 2-3 mm; anthers 0.4-0.5 mm; gynophore obsolete. Fruits ovoid, 4-angled, 3-5 × 2-3 mm; valves each with prominent midvein, keeled on back, puberulent; style 0.5-1 mm. Seeds brown, 1.8-2.5 × 1-1.5 mm.

Flowering May-Jun. Rocky slopes and ridges, pinyon-juniper woods, loose granitic rocks, rocky crevices and flats, dwarf sagebrush slopes; of conservation concern; 2400-2800 m; Calif., Nev.

Cusickiella quadricostata is narrowly restricted in California to Mono County and in Nevada to Lyon and Mineral counties.