Draba arctogena

Perennials; (cespitose); caudex branched (sometimes with persistent leaf remains); sometimes scapose. Stems unbranched, 0.3–1.4 dm, pubescent throughout, trichomes simple, 0.2–1 mm, and 2–6-rayed, 0.05–0.3 mm. Basal leaves rosulate; petiolate; petiole base and margin ciliate, (trichomes mostly simple, 0.2–1 mm); blade oblanceolate to narrowly obovate, 0.4–1.7 cm × 1.5–6 mm, margins entire or with 1–3 teeth on each side, surfaces pubescent with primarily simple trichomes, 0.3–1mm, abaxially mixed with stalked, 4–10-rayed ones, 0.1–0.2 mm. Cauline leaves 0 or 1; sessile; blade ovate to oblong, margins entire or toothed, surfaces pubescent as basal. Racemes 2–14 (–17) -flowered, ebracteate, elongated in fruit; rachis not flexuous, pubescent as stem. Fruiting pedicels suberect to ascending, straight, 1–5 (–7) mm, pubescent, trichomes simple and 2–4-rayed. Flowers: sepals ovate, 1.8–2.5 mm, pubescent, (trichomes simple and short-stalked, 2–4-rayed); petals white, spatulate, 3–4 × 1.5–2 mm; anthers ovate, 0.3–0.4 mm. Fruits oblong, plane, flattened, 4–9 × 2–3.5 mm; valves pubescent, trichomes short-stalked, 2–4-rayed, 0.1–0.5 mm, sometimes with simple ones; ovules 20–32 per ovary; style 0.1–0.4 mm (stigma distinctly wider than style). Seeds ovoid, 0.7–1 × 0.5–0.6 mm. 2n = 48.

Phenology: Flowering Jun–Jul.
Habitat: Scree, sandy hills, gravel flats
Elevation: 0-450 m

Greenland, N.W.T., Nunavut.

Discussion

Draba arctogena is sometimes confused with D. norvegica, from which it differs by having less elongated fruiting racemes, abaxial leaf surfaces with 4–10-rayed (versus cruciform or, rarely, 2–6-rayed) trichomes, and fruits with 2–4-rayed trichomes, 0.1–0.5 mm, (versus glabrous or with simple and 2–4-rayed trichomes, 0.05–0.25 mm). The limits of D. arctica, D. arctogena, D. cinerea, and D. oblongata need to be critically evaluated in light of molecular and cytological data.

Selected References

None.

Lower Taxa