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FNA | Family List | FNA Vol. 7 | Brassicaceae | Draba

7. Draba arctica J. Vahl in G. C. Oeder et al., Fl. Dan. 13(39): plate 5, 2294. 1840.

Draba arctica subsp. ostenfeldii Böcher ex Kartesz & Gandhi; D. arctica var. ostenfeldii Böcher ex Kartesz & Gandhi; D. cinerea Adams var. arctica (J. Vahl) Pohle; D. ostenfeldii E. Ekman 1929, not D. ×ostenfeldii O. E. Schulz 1927; D. ostenfeldii var. ovibovina E. Ekman; D. ovibovina (E. Ekman) E. Ekman ex Gelting

Perennials; (cespitose, not pulvinate); caudex simple or branched; rarely scapose. Stems unbranched, 0.3-1.7 (-2.4) dm, pubescent, trichomes 4-10-rayed (rays sometimes branched), 0.1-0.3 mm, with fewer, simple ones, to 0.7 mm. Basal leaves rosulate; petiolate; petiole base ciliate, (trichomes simple, 0.2-0.8 mm); blade oblanceolate to narrowly obovate, 0.4-2.3(-3) cm × 1.5-6.5 mm, margins usually entire, rarely with 1 tooth on each side, surfaces densely pubescent with minutely stalked, 8-12-rayed, stellate trichomes, 0.2-0.4 mm, sometimes with coarser, simple or 2-rayed ones, (midvein distinct abaxially). Cauline leaves 0 or 1(-3); sessile; blade ovate or oblong to lanceolate, margins entire, surfaces pubescent as basal. Racemes 3-18(-25)-flowered, ebracteate, elongated in fruit; rachis not flexuous, pubescent as stem. Fruiting pedicels divaricate-ascending or ascending, straight, (1.5-)2-6 mm, pubescent, trichomes stalked, stellate, and, sometimes, simple. Flowers: sepals ovate, 2-2.5 mm, pubescent, (trichomes short-stalked, 2- or 3-rayed, and simple); petals white, spatulate to obovate, 3.5-6 × 1.8-2 mm; anthers ovate, 0.3-0.4 mm. Fruits oblong to lanceolate, plane, slightly flattened, (5-)6-11 × 2-3 mm; valves pubescent, trichomes short-stalked, 2-5-rayed (some rays branched), 0.05-0.3 mm; ovules 20-32 per ovary; style 0.1-1 mm (stigma distinctly wider than style). Seeds ovoid, 0.8-1.1 × (0.6-)0.7-0.8 mm. 2n = 80.

Flowering Jun-Jul. Clay flats, gravel, beaches, limestone outcrops, talus; 0-500 m; Greenland; Nunavut; Europe (Norway [Svalbard]).

As circumscribed here, Draba arctica consists of two distinct elements often recognized as subspecies (arctica and ostenfeldii; T. W. Böcher 1966); perhaps they are better treated as distinct species (D. arctica and D. ovibovina). Lack of adequate material and inability to examine all of the types in this complex prevent us from doing so.


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