Draba corymbosa |
Draba incrassata |
|
---|---|---|
Baffin bay Draba, Baffin bay whitlow-grass, flat-top Draba |
Sweetwater Draba, Sweetwater Mountains. Draba |
|
Habit | Perennials; (cespitose); caudex branched (with persistent leaves or leaf remains, branches sometimes terminating in sterile rosettes); scapose. | Perennials; (cespitose, loosely matted); caudex branched (with persistent leaf bases, branches often creeping, 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, 0.2–0.8 dm, glabrous throughout. |
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; subsessile; petiole ciliate; blade (thick and somewhat fleshy), obovate to spatulate or oblanceolate, 0.3–1 cm × 1.5–4.5 mm, margins entire, (sometimes sparsely ciliate), surfaces glabrous or pubescent proximal to apex, with simple and fewer, short-stalked, 2-rayed trichomes, 0.2–0.7 mm. |
Cauline leaves | 0. |
0. |
Racemes | 2–9(–12)-flowered, ebracteate, (corymbose), slightly elongated in fruit; rachis not flexuous, pubescent as stem. |
8–22-flowered, ebracteate, elongated in fruit; rachis not flexuous, glabrous. |
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 oblong, 1.7–3 mm, glabrous or pubescent, (trichomes subapical, simple or 2-rayed); petals bright yellow, oblanceolate to spatulate, 3–5 × 1.7–2.5 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 (distinctly decurrent basally), curved upward, 3–7(–10) mm, glabrous. |
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 or narrowly elliptic-lanceolate, plane, flattened, 3–7(–10) × 2.2–4.5 mm; valves usually glabrous, rarely sparsely puberulent, trichomes simple, 0.03–0.1 mm; ovules 8–12 per ovary; style 0.2–0.8 mm. |
Seeds | (brown), ovoid, 1–1.3 × 0.6–0.9 mm. |
oblong, 1.5–1.8 × 0.8–1.1 mm. |
2n | = 128, 144. |
= 24. |
Draba corymbosa |
Draba incrassata |
|
Phenology | Flowering Jun–Aug. | Flowering Jun–Aug. |
Habitat | Moist tundra, among calcareous or dolomitic rocks, gravel beaches, silt and clay terraces | Rocky and gravelly slopes, alpine fellfields |
Elevation | 0-1700 m (0-5600 ft) | 2500-3500 m (8200-11500 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.) |
Although originally treated as a variety of Draba lemmonii, D. incrassata is quite distinct both morphologically (R. A. Price and R. C. Rollins 1991) and chromosomally (M. D. Windham, unpubl.). The species is known from the Sweetwater Mountains in Mono County. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 301. | FNA vol. 7, p. 313. |
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 | D. lemmonii var. incrassata |
Name authority | R. Brown ex de Candolle: Syst. Nat. 2: 343. (1821) | (Rollins) Rollins & R. A. Price: Harvard Pap. Bot. 1(3): 73. (1991) |
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