Draba alpina |
Draba ramosissima |
|
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alpine Draba |
branch Draba |
|
Habit | Perennials; (cespitose); caudex branched (covered with persistent leaves or leaf remains); scapose. | Perennials; caudex branched (well-developed, with persistent leaf bases); not scapose. |
Stems | unbranched, (0.3–)0.5–1.7(–2.8) dm, pubescent throughout, trichomes simple and 2-rayed, 0.3–0.8 mm, with 3–5-rayed ones, 0.1–0.3 mm. |
unbranched proximally, paniculately branched distally, 0.7–3.8(–5) dm, pubescent proximally, trichomes short-stalked, 2–4-rayed, 0.1–0.6 mm, sometimes with simple ones, 0.4–0.8 mm. |
Basal leaves | rosulate; petiolate; petiole base (not thickened), ciliate, (trichomes simple, 0.3–1 mm); blade oblanceolate to obovate or lanceolate to oblong, 0.8–3(–4.5) cm × 2.5–6(–9) mm, margins entire, surfaces abaxially pubescent with stalked, 2–4-rayed trichomes, 0.1–0.5 mm, with simple ones (midvein obscure, not thickened), adaxially glabrous or sparsely pubescent with simple and stalked, 2–4-rayed trichomes. |
rosulate; petiolate; petiole (to 2 cm), ciliate (trichomes simple, 0.3–0.5 mm); blade oblanceolate, (0.7–)1–5.5 cm × 2–8 mm, margins dentate, surfaces pubescent with short-stalked to subsessile, 3- or 4-rayed trichomes, 0.1–0.5 mm, adaxially sometimes also simple, 0.4–1.3 mm. |
Cauline leaves | 0. |
(5–)7–15(–21); sessile; blade ovate to oblong or elliptic to lanceolate, margins usually coarsely dentate or serrate, rarely subpinnatifid, surfaces pubescent as basal. |
Racemes | 6–18-flowered, ebracteate, considerably elongated in fruit; rachis not flexuous, pubescent as stem. |
9–28-flowered, ebracteate, paniculate; rachis not flexuous, pubescent as stem. |
Flowers | sepals (purplish tinged), narrowly ovate, 2.5–3 mm, pubescent, (trichomes simple and fewer, stalked, 2-rayed); petals bright yellow, narrowly obovate, 3.5–5 × 1.7–2.5 mm; anthers ovate, 0.3–0.4 mm. |
sepals oblong, 2.5–3 mm, pubescent, (trichomes simple and subsessile, 2–4-rayed); petals white, spatulate, 4–6 × 1.5–2.5 mm; anthers oblong, 0.5–0.6 mm. |
Fruiting pedicels | ascending to divaricate-ascending, straight or, sometimes, slightly curved upwards, 4–14(–30) mm, pubescent, trichomes simple and 2–4-rayed. |
horizontal to divaricate-ascending, straight, (4–)6–12(–15) mm, pubescent, trichomes 2–4-rayed. |
Fruits | elliptic, plane, flattened, 6–10 × 2–3 mm; valves glabrous or glabrescent, trichomes simple, (not confined to replum); ovules 12–24 per ovary; style 0.2–0.3 mm (stigma about as wide as style). |
narrowly oblong to elliptic or oblong-lanceolate, often strongly twisted, flattened, 5–11 × 1.5–2.2 mm; valves pubescent, trichomes subsessile or sessile, 2–4-rayed, 0.07–0.3 mm; ovules 4–10(–12) per ovary; style (1)1.5–3(–4) mm, (sparsely pubescent). |
Seeds | (pale brown), ovoid, 0.9–1.3 × 0.6–0.9 mm. |
oblong, 1.2–1.8 × 0.6–0.9 mm. |
2n | = 80. |
= 16. |
Draba alpina |
Draba ramosissima |
|
Phenology | Flowering Jun–Aug. | Flowering Apr–Jun. |
Habitat | Moist tundra and ridges, sand and gravel flats or beaches | Limestone cliffs and outcrops, shale barrens, rocky wooded areas |
Elevation | 0-1000 m (0-3300 ft) | 0-1100 m (0-3600 ft) |
Distribution |
LB; MB; NU; ON; QC; Greenland; Europe (Finland, Norway, Russia, Sweden)
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DC; KY; MD; NC; TN; VA; WV |
Discussion | The synonymy above includes two North American names overlooked by C. L. Hitchcock (1941) and R. C. Rollins (1993). Draba alpina was broadly delimited by O. E. Schulz (1927) and included 17 varieties, some of which (e.g., corymbosa, oxycarpa, pilosa) are recognized herein as distinct species. The name D. alpina was so misapplied that it was used for any circumpolar or alpine, scapose, yellow-flowered, perennial Draba. Various chromosome numbers (e.g., 2n = 64, 80, 112, 120; S. I. Warwick and I. A. Al-Shehbaz 2006) have been reported for the species. As circumscribed here, it has the narrow distribution outlined above and includes plants with 2n = 80. Reports of the species from Alaska, Canadian Northwest Territories and Yukon, Siberia, eastern Asia, Russian Far East, and the Central Asian republics are either suspect or very unlikely. The entire D. alpina complex (including the above three species, D. glacialis Adams, D. macounii, etc.) is in need of critical molecular, cytological, and morphological study. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
|
Source | FNA vol. 7, p. 290. | FNA vol. 7, p. 332. |
Parent taxa | Brassicaceae > tribe Arabideae > Draba | Brassicaceae > tribe Arabideae > Draba |
Sibling taxa | ||
Synonyms | D. alpina var. hydeana, D. alpina var. inflatisiliqua | Alyssum dentatum, D. dentata, D. ramosissima var. glabrifolia |
Name authority | Linnaeus: Sp. Pl. 2: 642. (1753) | Desvaux: J. Bot. Agric. 3: 186. (1815) |
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