Draba globosa |
Draba crassifolia |
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beavertip Draba, rockcress Draba, round-fruit Draba |
Rocky Mountain Draba, Rocky Mountain whitlow-grass, snowbed Draba, snowbed whitlow-grass, thick-leaf Draba |
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Habit | Perennials; (cespitose, pulvinate); caudex branched (with persistent leaves, branches sometimes terminating in sterile rosettes); scapose. | Annuals or perennials; (short-lived); caudex branched (when present); usually scapose. |
Stems | unbranched, 0.1–0.5 dm, glabrous. |
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. |
Basal leaves | rosulate; sessile; blade (not fleshy), narrowly oblanceolate or lanceolate to linear, (0.2–)0.3–0.8 cm × 0.5–1.6(–2) mm, margins entire (ciliate, trichomes simple, 0.1–0.8 mm, apex acute, trichomes usually longer), surfaces glabrous, (midvein obscure abaxially). |
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. |
Cauline leaves | 0. |
usually 0, rarely 1; sessile; blade oblong to ovate, margins entire, surfaces glabrous. |
Racemes | 2–5(–7)-flowered, ebracteate, slightly elongated in fruit; rachis not flexuous, glabrous. |
(2–)4–15(–25)-flowered, ebracteate, elongated in fruit; rachis slightly flexuous or straight, glabrous. |
Flowers | sepals (persistent to near fruit maturity), ovate to broadly oblong, 2–3 mm, glabrous; petals white to pale yellow, obovate, 2.5–4 × 1.2–2 mm; anthers oblong, 0.4–0.6 mm. |
(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. |
Fruiting pedicels | divaricate-ascending, straight or slightly curved, 2–6 mm, glabrous. |
horizontal to divaricate-ascending, usually straight, rarely curved upward, 3–8(–10) mm (subequaling or shorter than fruit), glabrous. |
Fruits | ovate, plane, flattened, 4.5–8 × 2.5–4 mm; valves (distinctly veined), glabrous; ovules 8–16 per ovary; style (0.1–)0.2–0.6 mm. |
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. |
Seeds | oblong, 1.1–1.4 × 0.8–1 mm. |
elliptic, 0.7–0.8 × 0.4–0.5 mm. |
2n | = 40. |
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Draba globosa |
Draba crassifolia |
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Phenology | Flowering Jun–Aug. | Flowering Jun–Sep. |
Habitat | Ridges, talus, alpine tundra and meadows | Rock outcrops and talus, subalpine meadows, alpine summits and tundra, bare snow-melt areas |
Elevation | 2700-3900 m (8900-12800 ft) | (50-)1000-4300 m ((200-)3300-14100 ft) |
Distribution |
ID; MT; UT; WY
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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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Discussion | Draba globosa is an apomictic species closely related to D. burkei (M. D. Windham, unpubl.). Though often treated as a variety of D. densifolia, it is morphologically and phyletically distinct from that species. Both R. C. Rollins (1993) and N. H. Holmgren (2005b) indicated that the species occurs in Colorado, but we have not seen material for that state. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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.) |
Source | FNA vol. 7, p. 308. | FNA vol. 7, p. 302. |
Parent taxa | Brassicaceae > tribe Arabideae > Draba | Brassicaceae > tribe Arabideae > Draba |
Sibling taxa | ||
Synonyms | D. apiculata, D. densifolia var. apiculata, D. densifolia var. decipiens, D. densifolia var. globosa | D. crassifolia var. parryi, D. parryi |
Name authority | Payson: Amer. J. Bot. 4: 257. (1917) | Graham: Edinburgh New Philos. J. 7: 182. (1829) |
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