Amer. J. Bot. 4: 266. 1917
Perennials; (densely cespitose to pulvinate); caudex branched (with persistent leaves, branches sometimes terminating in sterile rosettes); scapose. Stems unbranched, 0.3–1.1 dm, pubescent throughout, trichomes sub-dendritic, 2–7-rayed, (often crisped), 0.2–0.7 mm. Basal leaves (densely imbricate); rosulate; petiolate; petiole base and margin ciliate, (trichomes simple or branched, often crisped, 0.3–1 mm); blade oblanceolate to obovate or spatulate, 0.2–0.7 cm × 1–2.8 mm, margins entire, surfaces densely pubescent (often grayish) with stellate-dendritic, stalked, 5–12-rayed, (often crisped) trichomes, 0.2–0.6 mm. Cauline leaves 0. Racemes 4–12-flowered, ebracteate, elongated in fruit; rachis not flexuous, pubescent as stem. Fruiting pedicels erect (and subappressed to rachis) or ascending, straight, (3–)4–9(–12) mm, pubescent as stem. Flowers: sepals oblong, 3–4 mm, pubescent, (trichomes stalked, branched, crisped); petals yellow, oblanceolate, 6–7 × 1.5–2.5 mm; anthers oblong, 0.7–0.9 mm. Fruits broadly ovate to lanceolate or subelliptic, plane, flattened, 5–10(–13) × (2.5–)3.5–5(–6) mm; valves pubescent, trichomes short stalked, 2–7-rayed, (straight or crisped), 0.15–0.6 mm; ovules 8–12 per ovary; style 1.5–3(–3.8) mm. Seeds (winged), ovate, 1.6–3 × 1.3–1.8 mm; (wing 0.3–0.9 mm wide).
Phenology: Flowering Jun–Sep.
Habitat: Limestone and marble outcrops, talus, gravel slopes
Elevation: 1500-2500 m
Draba pterosperma is a distinctive species that is restricted to the Marble Mountains of northern California (Siskiyou County).