Draba corymbosa |
Draba aprica |
|
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Baffin bay Draba, Baffin bay whitlow-grass, flat-top Draba |
hairy Draba, openground Draba |
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Habit | Perennials; (cespitose); caudex branched (with persistent leaves or leaf remains, branches sometimes terminating in sterile rosettes); scapose. | Annuals; not 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). |
usually branched distally, (0.3–)0.7–3(–3.6) dm, pubescent throughout, trichomes short-stalked to subsessile, cruciform, 0.1–0.5 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. |
not rosulate; petiolate; petiole (to 1 cm), ciliate throughout; blade obovate to spatulate or ovate to suborbicular, 0.6–2.5 cm × 3–10 mm, margins usually entire, rarely toothed, surfaces pubescent with stalked, cruciform trichomes, 0.1–0.5 mm. |
Cauline leaves | 0. |
(5–)8–20(–25); sessile; blade oblong to lanceolate, margins entire, (not ciliate), surfaces pubescent as basal. |
Racemes | 2–9(–12)-flowered, ebracteate, (corymbose), slightly elongated in fruit; rachis not flexuous, pubescent as stem. |
7–46-flowered, ebracteate, elongated in fruit, (lateral racemes from axils of distalmost leaves subumbellate); rachis not flexuous, pubescent 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. |
(late ones cleistogamous, apetalous); sepals oblong, 0.6–1.2 mm, pubescent; petals white, spatulate, 1.3–2.5 × 0.5–1 mm; anthers ovate, 0.1–0.2(–0.05 in cleistogamous flowers) 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, straight, 2–5 mm, pubescent, trichomes subsessile, 4-rayed. |
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). |
linear-ellipsoid to ellipsoid, plane, flattened, (3–)4–6 × 0.8–1.1 mm; valves pubescent, trichomes subsessile, (2–)4-rayed, 0.03–0.12 mm; ovules 4–6(–8) per ovary; style 0.07–0.13 mm. |
Seeds | (brown), ovoid, 1–1.3 × 0.6–0.9 mm. |
ovoid, 0.9–1.1 × 0.5–0.6 mm. |
2n | = 128, 144. |
|
Draba corymbosa |
Draba aprica |
|
Phenology | Flowering Jun–Aug. | Flowering Mar–May. |
Habitat | Moist tundra, among calcareous or dolomitic rocks, gravel beaches, silt and clay terraces | Open knolls, rocky roadsides, rock outcrops, igneous glades, woods, alluvial areas near streams |
Elevation | 0-1700 m (0-5600 ft) | 100-400 m (300-1300 ft) |
Distribution |
AK; BC; NT; NU; YT; Greenland; Europe (Norway, n Russia); e Asia (Russian Far East, Siberia) |
AR; GA; MO; OK; SC
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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.) |
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Source | FNA vol. 7, p. 301. | FNA vol. 7, p. 290. |
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. brachycarpa var. fastigiata |
Name authority | R. Brown ex de Candolle: Syst. Nat. 2: 343. (1821) | Beadle: in J. K. Small, Fl. S.E. U.S. ed. 2, 1336, 1375. (1913) |
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