Draba corymbosa |
Draba viridis |
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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. | Perennials; (long-lived, cespitose); caudex simple or branched (densely covered with persistent petioles); 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). |
unbranched or branched, 0.35–3 dm, pubescent throughout, trichomes simple, 0.2–0.8 mm, with short-stalked to subsessile, cruciform ones, 0.05–0.2 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; petiolate; petiole ciliate, (trichomes simple, 0.4–1 mm); blade oblanceolate, 1–6 cm × 2–6 mm, margins usually entire, rarely denticulate, surfaces pubescent with stalked, cruciform trichomes, 0.1–0.5 mm. |
Cauline leaves | 0. |
5–16; sessile; blade ovate to lanceolate or oblong, margins entire or denticulate, surfaces pubescent as basal. |
Racemes | 2–9(–12)-flowered, ebracteate, (corymbose), slightly elongated in fruit; rachis not flexuous, pubescent as stem. |
11–28-flowered, ebracteate, elongated in fruit; 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. |
sepals oblong, 2–3 mm, pubescent, (trichomes simple and 2-rayed); petals yellow, oblanceolate, 3.5–5 × 1–1.5 mm; anthers ovate, 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, straight, 4–7 mm, pubescent throughout, trichomes simple (0.1–0.4 mm) and subsessile, 2–4-rayed (0.03–0.25 mm). |
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). |
lanceolate to ovate, often plane, flattened, 3.5–8 × 2–3 mm; valves pubescent, trichomes (vertical), simple and 2–4-rayed, (0.1–)0.3–0.8 mm; ovules 12–20 per ovary; style (1.5–)2–3 mm. |
Seeds | (brown), ovoid, 1–1.3 × 0.6–0.9 mm. |
ovoid, 1.2–1.5 × 0.7–0.9 mm. |
2n | = 128, 144. |
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Draba corymbosa |
Draba viridis |
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Phenology | Flowering Jun–Aug. | Flowering Aug–Sep. |
Habitat | Moist tundra, among calcareous or dolomitic rocks, gravel beaches, silt and clay terraces | Open stands of pines |
Elevation | 0-1700 m (0-5600 ft) | ca. 2600 m (ca. 8500 ft) |
Distribution |
AK; BC; NT; NU; YT; Greenland; Europe (Norway, n Russia); e Asia (Russian Far East, Siberia) |
AZ; Mexico (Sonora) |
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.) |
Of conservation concern. Draba viridis has been reported from the Huachuca and Santa Catalina mountains in southern Arizona, and the adjacent San Jose Mountains in Sonora, Mexico. It was reduced to a variety of D. petrophila by Hitchcock and a form of D. helleriana by O. E. Schulz, but is easily separated from both (I. A. Al-Shehbaz and M. D. Windham 2007). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 301. | FNA vol. 7, p. 345. |
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. petrophila var. viridis |
Name authority | R. Brown ex de Candolle: Syst. Nat. 2: 343. (1821) | A. Heller: Muhlenbergia 1: 27. (1901) |
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