Draba cana |
Draba palanderiana |
|
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Brewer's Draba, canescent Draba, canescent whitlow-mustard, cushion Draba, hoary Draba, hoary whitlow-grass, lance-leaf Draba, lance-leaf whitlow-grass |
palander's Draba, palander's whitlow-grass |
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Habit | Perennials; caudex simple or branched (branches short); not scapose. | Perennials; (cespitose); caudex branched (with persistent leaf remains, branches sometimes terminating in sterile rosettes); scapose. |
Stems | unbranched or branched distally, (0.6–)1–3(–3.8) dm, pubescent throughout, trichomes simple, 0.5–1mm, with 4–10-rayed ones, 0.05–0.2 mm (mostly branched on basal parts). |
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 linear to oblanceolate or oblong, (0.5–)0.8–2(–3.5) cm × 1.5–4(–11) mm, margins entire or dentate, (base and apex ciliate, trichomes simple, 0.3–0.8 mm), surfaces pubescent with short-stalked, 4–12-rayed trichomes, 0.1–0.3 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 | 3–10(–17), (not overlapping); sessile; blade lanceolate to ovate or oblong, margins entire or dentate, surfaces pubescent as basal (adaxially with simple and forked trichomes near blade base). |
0. |
Racemes | (10–)15–47(–63)-flowered, basally bracteate, often considerably elongated in fruit; rachis not flexuous, densely pubescent, trichomes 4–10-rayed (0.05–0.2 mm), and fewer simple ones. |
5–17-flowered, ebracteate, elongated in fruit; rachis not flexuous, usually glabrous, rarely sparsely pubescent as stem. |
Flowers | sepals (green or lavender), oblong to ovate, 1.5–2 mm, pubescent, (trichomes simple and few-rayed); petals white, oblanceolate to spatulate, 2.3–3.7(–4.5) × 0.7–1.7 mm; anthers ovate, 0.1–0.2 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 | suberect or ascending, straight, 2–5(–10) mm, pubescent as rachis. |
divaricate-ascending, straight, (slender), 4–10 mm, usually glabrous, rarely sparsely pubescent as stem. |
Fruits | (subappressed to rachis), linear-lanceolate to linear or, rarely, ovate-oblong, slightly twisted or plane, flattened, (5–)6–11 × 1.5–2(–2.5) mm; valves pubescent, trichomes short-stalked, 3–7-rayed, 0.05–0.3 mm; ovules 28–48 per ovary; style 0.1–0.6 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 | ovoid, 0.5–0.7(–0.9) × 0.3–0.5 mm. |
ovoid, 0.9–1.1 × 0.5–0.7 mm. |
2n | = 32. |
= 16, 32, 64. |
Draba cana |
Draba palanderiana |
|
Phenology | Flowering (May-)Jun–Aug. | Flowering Jun–Jul. |
Habitat | Rock outcrops and talus, open prairie benchlands, roadsides, meadows, alpine tundra | Rock outcrops, talus, Dryas fellfields, tundra |
Elevation | 0-4100 m (0-13500 ft) | 0-1800 m (0-5900 ft) |
Distribution |
AK; CA; CO; ID; ME; MI; MT; NH; NM; NV; SD; UT; VT; WA; WI; WY; AB; BC; MB; NB; NF; NT; ON; QC; SK; YT; Greenland
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AK; NT; YT; e Asia (Russian Far East, Siberia) |
Discussion | The limits of Draba cana have long been confused, and the species was treated as a synonym of the Himalayan D. lanceolata Royle (M. L. Fernald 1934; C. L. Hitchcock 1941) or as a variety of the western North American D. breweri (R. C. Rollins 1993). However, G. A. Mulligan (1971) clearly demonstrated that all three are distinct and should be maintained. Some Utah plants corresponding to the type of D. valida have shorter and wider oblong-ovate fruits. In all other aspects, they are indistinguishable from D. cana. Additional studies are needed to establish whether such plants should be formally recognized. (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. 298. | FNA vol. 7, p. 326. |
Parent taxa | Brassicaceae > tribe Arabideae > Draba | Brassicaceae > tribe Arabideae > Draba |
Sibling taxa | ||
Synonyms | D. breweri var. cana, D. valida | |
Name authority | Rydberg: Bull. Torrey Bot. Club 29: 241. (1902) | Kjellman: in A. E. Nordenskiöld, Vega Exp. Vetensk. Iakttag. 2: 45. (1883) |
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