Draba corymbosa |
Draba longisquamosa |
|
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Baffin bay Draba, Baffin bay whitlow-grass, flat-top Draba |
granite Draba |
|
Habit | Perennials; (cespitose); caudex branched (with persistent leaves or leaf remains, branches sometimes terminating in sterile rosettes); scapose. | Perennials; (cespitose); 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, 0.2–0.9 dm, hirsute throughout, trichomes simple, 0.2–0.8 mm. |
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, 0.1–1 mm); blade oblanceolate to obovate, 0.5–2 cm × 2–5 mm, margins entire, surfaces pubescent with simple trichomes, 0.15–0.8 mm. |
Cauline leaves | 0. |
0. |
Racemes | 2–9(–12)-flowered, ebracteate, (corymbose), slightly elongated in fruit; rachis not flexuous, pubescent as stem. |
4–16-flowered, ebracteate, (subumbellate), slightly 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 (persistent) ovate, 1.5–2.2 mm, pubescent, (trichomes simple); petals (persistent), yellow, spatulate, 3.5–5 × 1.5–2 mm; anthers oblong, 0.5–0.6 mm. |
Fruiting pedicels | divaricate-ascending, straight or slightly curved upward, 4–11(–16) mm, pubescent, trichomes simple and 2–4-rayed. |
divaricate to ascending (not decurrent basally), straight, 3–7 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 suborbicular, plane, flattened, 3.5–7 × 2.5–5 mm; valves pubescent, trichomes simple, 0.1–0.3 mm; ovules 10–16 per ovary; style 0.4–1 mm. |
Seeds | (brown), ovoid, 1–1.3 × 0.6–0.9 mm. |
ovoid, 1–1.2 × 0.7–0.8 mm. |
2n | = 128, 144. |
|
Draba corymbosa |
Draba longisquamosa |
|
Phenology | Flowering Jun–Aug. | Flowering Jul. |
Habitat | Moist tundra, among calcareous or dolomitic rocks, gravel beaches, silt and clay terraces | Gravelly areas |
Elevation | 0-1700 m (0-5600 ft) | 3000-3900 m (9800-12800 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 longisquamosa was treated as a synonym of D. lemmonii by both C. L. Hitchcock (1941) and R. C. Rollins (1993). We feel that the two taxa show sufficient morphological divergence and merit recognition as separate species (see I. A. Al-Shehbaz and M. D. Windham 2007 for more detailed discussion). Draba longisquamosa is currently known only from the southern Sierra Nevada in Fresno, Inyo, and Tulare counties. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 301. | FNA vol. 7, p. 317. |
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) | O. E. Schulz: in H. G. A. Engler, Pflanzenr. 89[IV,105]: 94. (1927) |
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