Draba crassifolia |
Draba palanderiana |
|
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Rocky Mountain Draba, Rocky Mountain whitlow-grass, snowbed Draba, snowbed whitlow-grass, thick-leaf Draba |
palander's Draba, palander's whitlow-grass |
|
Habit | Annuals or perennials; (short-lived); caudex branched (when present); usually scapose. | Perennials; (cespitose); caudex branched (with persistent leaf remains, branches sometimes terminating in sterile rosettes); scapose. |
Stems | unbranched or, rarely, branched distally, (0.1–)0.3–1.1(–1.5) dm, usually glabrous throughout, rarely pubescent proximally, trichomes simple, 0.3–0.7 mm. |
unbranched, 0.2–1.1(–1.5) dm, pubescent proximally, trichomes 2–9-rayed, 0.05–0.2 mm, glabrous or sparsely pubescent distally. |
Basal leaves | rosulate; petiolate; petiole ciliate throughout; blade oblanceolate to obovate, (0.2–) 0.5–2.5(–3) cm × (1–)2–4(–6) mm, margins usually entire, rarely denticulate, (sometimes ciliate), surfaces glabrous or sparsely pubescent, with simple and 2-rayed trichomes, 0.3–0.9 mm. |
rosulate; petiolate; petiole (thickened), ciliate proximally, (margin not ciliate, trichomes simple and 2-rayed, 0.2–0.5 mm); blade oblanceolate to obovate, 0.3–0.9(–1.5) cm × 1–4 mm, margins usually entire, rarely denticulate, surfaces pubescent with minutely stalked, 8–16-rayed, stellate trichomes, 0.08–0.3 mm, (midvein obscure abaxially). |
Cauline leaves | usually 0, rarely 1; sessile; blade oblong to ovate, margins entire, surfaces glabrous. |
0. |
Racemes | (2–)4–15(–25)-flowered, ebracteate, elongated in fruit; rachis slightly flexuous or straight, glabrous. |
5–17-flowered, ebracteate, elongated in fruit; rachis not flexuous, usually glabrous, rarely sparsely pubescent as stem. |
Flowers | (chasmogamous, petaliferous); sepals (green or purplish), ovate, 1–2 mm, glabrous; petals yellow (often fading white), oblanceolate, 1.5–2.5(–3) × 0.5–1 mm; anthers ovate, 0.15–0.25 mm. |
sepals ovate, 2–2.5 mm, pubescent, (trichomes simple and short-stalked, 2–6-rayed); petals white or creamy white, obovate, 4.5–5.5 × 2–3 mm; anthers ovate, 0.4–0.6 mm. |
Fruiting pedicels | horizontal to divaricate-ascending, usually straight, rarely curved upward, 3–8(–10) mm (subequaling or shorter than fruit), glabrous. |
divaricate-ascending, straight, (slender), 4–10 mm, usually glabrous, rarely sparsely pubescent as stem. |
Fruits | usually narrowly elliptic to lanceolate, rarely linear-lanceolate, plane, flattened, (3–)5–10 × 1.5–2.5 mm; valves glabrous; ovules (8–)16–24(–30) per ovary; style 0.02–0.1 mm. |
(often aborting, becoming lopsided), oblong to elliptic or ovate, plane, flattened, 4–8 × 2–3 mm; valves glabrous; ovules 18–32 per ovary; style 0.3 0.8 mm. |
Seeds | elliptic, 0.7–0.8 × 0.4–0.5 mm. |
ovoid, 0.9–1.1 × 0.5–0.7 mm. |
2n | = 40. |
= 16, 32, 64. |
Draba crassifolia |
Draba palanderiana |
|
Phenology | Flowering Jun–Sep. | Flowering Jun–Jul. |
Habitat | Rock outcrops and talus, subalpine meadows, alpine summits and tundra, bare snow-melt areas | Rock outcrops, talus, Dryas fellfields, tundra |
Elevation | (50-)1000-4300 m ((200-)3300-14100 ft) | 0-1800 m (0-5900 ft) |
Distribution |
AK; AZ; CO; ID; MT; NM; NV; UT; WA; WY; AB; BC; LB; NT; NU; QC; YT; Greenland; n Europe (Norway, Sweden)
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AK; NT; YT; e Asia (Russian Far East, Siberia) |
Discussion | M. D. Windham (2004) presented morphological and chromosomal data suggesting that Draba crassifolia is an allopolyploid produced by hybridization between D. albertina and D. fladnizensis. Although the species is distinctive in large part, some individuals can be difficult to place and there is evidence of rare backcrossing (Windham, unpubl.). The attribution to Arizona is based on Schaack 345 (US) and Kearney & Peebles 12156 (US), both collected on the San Francisco Peaks in Coconino County. Draba crassifolia is found at elevations as low as 50 m in Greenland and the islands of Nunavut. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
North American plants of Draba palanderiana are diploid and appear to be self-incompatible, an unusual situation among arctic members of the genus. By contrast, some plants from the Russian Far East are tetraploid (2n = 32) or octoploid (2n = 64) and appear to be self-compatible. Detailed studies are needed to establish whether one or two taxa are involved. Many North American collections of Draba palanderiana have been misidentified as D. nivalis. The species is easily separated from D. nivalis by having ciliate (versus non-ciliate) bases of basal leaves, larger petals (4.5–5.5 × 2–3 versus 2–3.5 × 0.8–1.4 mm) that are pale yellow or cream (versus white), and longer fruiting pedicels 4–10 [versus 1–4.5(–8)] mm. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 302. | FNA vol. 7, p. 326. |
Parent taxa | Brassicaceae > tribe Arabideae > Draba | Brassicaceae > tribe Arabideae > Draba |
Sibling taxa | ||
Synonyms | D. crassifolia var. parryi, D. parryi | |
Name authority | Graham: Edinburgh New Philos. J. 7: 182. (1829) | Kjellman: in A. E. Nordenskiöld, Vega Exp. Vetensk. Iakttag. 2: 45. (1883) |
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