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.

Phenology: Flowering Jun–Jul.
Habitat: Meadows, mesic tundra, swales, gravelly soils
Elevation: 0-900 m

Distribution

• Generated Map
• Legacy Map

Greenland, N.W.T., Nunavut, Alaska, Europe (Norway [Spitsbergen]), e Asia (Russian Far East, Siberia).

Discussion

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.

Selected References

None.

Lower Taxa

None.