Draba corymbosa |
Brassicaceae tribe Arabideae |
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Baffin bay Draba, Baffin bay whitlow-grass, flat-top Draba |
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Habit | Perennials; (cespitose); caudex branched (with persistent leaves or leaf remains, branches sometimes terminating in sterile rosettes); scapose. | Annuals, biennials, or perennials [subshrubs]; eglandular. |
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). |
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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. |
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Cauline leaves | 0. |
petiolate or sessile; blade base auriculate or not, margins entire or dentate. |
Racemes | 2–9(–12)-flowered, ebracteate, (corymbose), slightly elongated in fruit; rachis not flexuous, pubescent as stem. |
usually ebracteate, often elongated in fruit. |
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. |
actinomorphic; sepals erect, ascending, or spreading, lateral pair seldom saccate basally; petals white, yellow, orange, pink, or purple, claw usually present, usually distinct; filaments unappendaged, not winged; pollen 3-colpate. |
Fruiting pedicels | divaricate-ascending, straight or slightly curved upward, 4–11(–16) mm, pubescent, trichomes simple and 2–4-rayed. |
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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). |
silicles or siliques, usually dehiscent, very rarely indehiscent, unsegmented, latiseptate or terete; ovules 2–70(–88)[–110+] per ovary; style usually distinct, sometimes obsolete; stigma usually entire, rarely 2-lobed. |
Seeds | (brown), ovoid, 1–1.3 × 0.6–0.9 mm. |
biseriate or uniseriate [rarely aseriate]; cotyledons accumbent. |
Trichomes | stalked or sessile, usually stellate, dendritic, cruciform, or forked, sometimes mixed with simple ones, rarely malpighiaceous. |
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2n | = 128, 144. |
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Draba corymbosa |
Brassicaceae tribe Arabideae |
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Phenology | Flowering Jun–Aug. | |
Habitat | Moist tundra, among calcareous or dolomitic rocks, gravel beaches, silt and clay terraces | |
Elevation | 0-1700 m (0-5600 ft) | |
Distribution |
AK; BC; NT; NU; YT; Greenland; Europe (Norway, n Russia); e Asia (Russian Far East, Siberia) |
North America; Mexico; South America; Europe; Asia; n Africa |
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.) |
Genera 8, species ca. 460 (4 genera, 139 species in the flora). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 301. | FNA vol. 7, p. 256. |
Parent taxa | Brassicaceae > tribe Arabideae > Draba | Brassicaceae |
Sibling taxa | ||
Subordinate 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) | de Candolle: Mém. Mus. Hist. Nat. 7: 229. (1821) |
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