Draba micropetala

Perennials; caudex branched (with persistent leaf remains); scapose. Stems unbranched, (0.05-)0.15-0.7(-1.1) dm, pubescent throughout, sometimes sparsely so distally, trichomes stalked, 2-4-rayed, and simple, 0.05-0.6 mm. Basal leaves (not imbricate); rosulate; petiolate; petiole (base thickened), margin ciliate, (trichomes coarse, simple and 2-rayed, 0.3-1.3 mm); blade broadly oblanceolate to broadly obovate, 0.6-2 cm × 4-12 mm, margins entire, (apex obtuse to rounded, trichomes multibranched, subcruciform), surfaces pubescent abaxially with stalked, 2-4-rayed and, rarely, simple trichomes, 0.1-0.6 mm, adaxially glabrous or with mostly simple trichomes. Cauline leaves 0. Racemes 2-7(-10)-flowered, ebracteate, often elongated in fruit; rachis often flexuous, pubescent as stem. Fruiting pedicels divaricate to ascending, straight, 1-3(-4) mm, pubescent as stem. Flowers: sepals oblong, 1.8-2.5 mm, pubescent, (trichomes simple, with short-stalked, 2-rayed ones); petals pale yellow, narrowly spatulate or oblanceolate, 2-3 × (0.7-) 1-1.5 mm; anthers ovate, 0.3-0.4 mm. Fruits elliptic-ovate, plane, slightly flattened, 5-10 × 2-3.2 mm; valves often densely pubescent, trichomes simple and spurred, 0.1-0.5 mm); ovules (16-)18-28 per ovary; style 0.05-0.3 mm (stigma about as wide as style). Seeds oblong, 1-1.1 × 0.5-0.6 mm. 2n = 48.

Flowering Jun-Jul. Meadows, mesic tundra, swales, gravelly soils; 0-900 m; Greenland; N.W.T., Nunavut; Alaska; Europe (Norway [Spitsbergen]); e Asia (Russian Far East, Siberia).

Draba micropetala, which was not listed by C. L. Hitchcock (1941) or R. C. Rollins (1993), is frequently confused with the closely related tetraploid (2n = 32) D. pauciflora. It is distinguished from the latter by having elongated (versus congested) fruiting racemes, narrower [2-3.2 versus (3-)3.5-5 mm] and elliptic-ovate (versus obovate) fruits, more [(16-)18-28 versus 8-16(-20)] seeds per fruit, and obtuse to rounded (versus subacute to acute) leaf apices with multibranched, subcruciform (versus simple and/or 2-branched) trichomes.