Draba subumbellata

Perennials; (cespitose, densely pulvinate); caudex branched (densely covered with persistent leaves and remains, branches tightly grouped, sometimes terminating in sterile rosettes); scapose. Stems unbranched, (0.05-)0.1-0.25 dm, densely pubescent throughout, trichomes (grayish), stalked, dendritic, 5-12-rayed, 0.1-0.25 mm. Basal leaves (densely imbricate); rosulate; sessile; blade obovate to broadly oblong, 0.2-0.4 cm × 0.6-1.5 mm, margins entire, (not ciliate), surfaces densely pubescent, trichomes (grayish), stalked, dendritic, 5-12-rayed, 0.1-0.3 mm, (sometimes with long-stalked and spurred trichomes adaxially). Cauline leaves 0. Racemes 2-5 (-10)-flowered, ebracteate, subumbellate or slightly elongated in fruit; rachis not flexuous, pubescent as stem. Fruiting pedicels divaricate-ascending, straight, 1.5-3(-6) mm, glabrous or pubescent as stem. Flowers: sepals broadly oblong, 1.8-2.8 mm, pubescent, (trichomes dendritic); petals yellow, spatulate, 2.8-4 × 1-1.5 mm; anthers ovate, 0.3-0.4 mm. Fruits ovoid to ovoid-lanceolate, plane, inflated and sometimes subgibbous basally, flattened distally, 2-5 × 2-3 mm; valves pubescent, trichomes short-stalked, dendritic, 4-12-rayed, (sometimes spurred), 0.05-0.2 mm; ovules 6-12 per ovary; style 0.2-0.6 mm. Seeds oblong, 1-1.2 × 0.5-0.7 mm.

Flowering Jul-Aug. Wind-eroded areas, alpine fellfields, rock crevices; 3300-4100 m; Calif., Nev.

Draba subumbellata is similar to, and sympatric with, D. oligosperma. It is distinguished from the latter by having stalked, stellate to dendritic leaf trichomes, subumbellate racemes, fruiting pedicels 1.5-3.0(-6.0) mm, fruits pubescent with mostly 4-12-rayed trichomes, and well-formed anthers and pollen. By contrast, D. oligosperma has sessile or subsessile, pectinately-branched leaf trichomes, elongated racemes, fruiting pedicels (2-)3-10(-13) mm, fruits glabrous or pubescent with simple and 2-rayed trichomes, and abortive anthers and/or pollen. Draba subumbellata is restricted to the White Mountains (Esmeralda County, Nevada, and Mono County, California) and to Coyote Ridge in the Sierra Nevada (Inyo County, California).