Draba corymbosa |
Draba lemmonii |
|
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Baffin bay Draba, Baffin bay whitlow-grass, flat-top Draba |
granite Draba, Lemmon's Draba |
|
Habit | Perennials; (cespitose); caudex branched (with persistent leaves or leaf remains, branches sometimes terminating in sterile rosettes); scapose. | Perennials; (cespitose, not pulvinate); caudex branched (covered with persistent petiole remains, branches sometimes terminating in sterile rosettes); scapose. |
Stems | unbranched, (0.05–)0.2–0.8(–1.5) dm, pubescent throughout, trichomes simple and 2-rayed, 0.4–1 mm, with 3–5-rayed ones, 0.05–0.4 mm, (sometimes trichomes mostly simple). |
unbranched, 0.3–1(–1.5) dm, hirsute throughout, trichomes simple, 0.2–0.7 mm, with short-stalked, 2-rayed ones, (smaller). |
Basal leaves | rosulate; petiolate; petiole base and margin ciliate, (trichomes often course, simple, 0.4–1.3 mm); blade oblanceolate to obovate, 0.6–1.8 cm × 1.5–5 mm, margins entire, surfaces pubescent, abaxially with stalked, 2–6-rayed trichomes, 0.2–0.6 mm, adaxially with primarily simple and stalked, 2-rayed trichomes, to 1.1 mm, with 3–5-rayed ones, 0.2–0.4 mm. |
rosulate; shortly petiolate; petiole base and margin ciliate, (trichomes simple, 0.5–1 mm, midvein obscure); blade (somewhat fleshy), oblanceolate to obovate, 0.4–1(–1.8) cm × 1.5–4(–6) mm, margins entire, surfaces hirsute, abaxially mostly with stalked, 2-rayed trichomes, 0.1–0.8 mm, rarely with fewer, simple ones, adaxially with mostly simple ones, 0.5–1 mm. |
Cauline leaves | 0. |
0. |
Racemes | 2–9(–12)-flowered, ebracteate, (corymbose), slightly elongated in fruit; rachis not flexuous, pubescent as stem. |
4–15(–21)-flowered, ebracteate, elongated in fruit; rachis not flexuous, hirsute as stem. |
Flowers | sepals (grayish green), broadly ovate, 2.2–3 mm, pubescent, (trichomes simple, to 1 mm, sometimes with stalked, smaller, 2–4-rayed ones); petals (broadly patent), yellow, obovate, 4–6 × 3–5 mm; anthers ovate, 0.3–0.4 mm. |
sepals ovate, 2–2.7 mm, pubescent, (trichomes simple, short-stalked, 2-rayed); petals yellow, spatulate, 4–6 × 1.5–2.5 mm; anthers oblong, 0.4–0.6 mm. |
Fruiting pedicels | divaricate-ascending, straight or slightly curved upward, 4–11(–16) mm, pubescent, trichomes simple and 2–4-rayed. |
horizontal to divaricate-ascending (often somewhat decurrent basally), straight or curved upward, 4–10(–14) mm, hirsute as stem. |
Fruits | oblong or ovate, plane, flattened, 6–12 × 3.5–5.5 mm; valves pubescent or puberulent, trichomes simple, 0.1–0.4 mm, (sometimes with short-stalked, 2- or 3-rayed ones); ovules 12–24 per ovary; style 0.6–1 mm (stigma distinctly wider than style). |
ovate to ovate-lanceolate, slightly twisted, flattened, 4–9 × 3.5–5 mm; valves pubescent, trichomes usually simple, 0.1–0.45 mm, rarely with fewer, short-stalked, 2-rayed ones; ovules 10–14(–16) per ovary; style 0.1–0.6(–0.8) mm. |
Seeds | (brown), ovoid, 1–1.3 × 0.6–0.9 mm. |
ovoid, 1–1.4 × 0.6–1 mm. |
2n | = 128, 144. |
= 50. |
Draba corymbosa |
Draba lemmonii |
|
Phenology | Flowering Jun–Aug. | Flowering Jul–Aug. |
Habitat | Moist tundra, among calcareous or dolomitic rocks, gravel beaches, silt and clay terraces | Granitic rock outcrops, boulder slopes, alpine fellfields |
Elevation | 0-1700 m (0-5600 ft) | 3000-4000 m (9800-13100 ft) |
Distribution |
AK; BC; NT; NU; YT; Greenland; Europe (Norway, n Russia); e Asia (Russian Far East, Siberia) |
CA
|
Discussion | Draba corymbosa, which is 16-ploid or 18-ploid with x = 8, is an extremely variable species of polyphyletic, allopolyploid origin. Most individuals appear to have decaploid D. alpina (2n = 80) in their parentage, but the other genomes are provided by hexaploid (2n = 48) and octoploid (2n = 64) species (C. Brochmann et al. 1993). O. E. Schulz reduced D. corymbosa to a variety of D. alpina; R. C. Rollins (1993) treated it as a distinct species. Draba corymbosa is distinguished from D. alpina by having pubescent or puberulent (versus glabrous or glabrescent) fruits, corymbose (versus usually elongated) fruiting racemes, and abaxial leaf blade surfaces always lacking (versus usually with some) simple trichomes. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Draba lemmonii was so broadly circumscribed by C. L. Hitchcock (1941) and R. C. Rollins (1993) that it included plants here assigned to three different species. For a list of features distinguishing D. lemmonii from the recently-segregated D. longisquamosa and D. cyclomorpha, see I. A. Al-Shehbaz and M. D. Windham (2007). Draba lemmonii is apparently restricted to alpine areas of the Sierra Nevada in Fresno, Inyo, Madera, Mono, and Tuolumne counties. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 301. | FNA vol. 7, p. 316. |
Parent taxa | Brassicaceae > tribe Arabideae > Draba | Brassicaceae > tribe Arabideae > Draba |
Sibling taxa | ||
Synonyms | D. alpina var. bellii, D. alpina var. corymbosa, D. barbata, D. bellii, D. kjellmanii, D. macrocarpa, D. vestita | |
Name authority | R. Brown ex de Candolle: Syst. Nat. 2: 343. (1821) | S. Watson: in W. H. Brewer et al., Bot. California 2: 430. (1880) |
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