Draba paucifructa |
Draba arctogena |
|
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Charleston Mountain Draba |
fellfield whitlowgrass |
|
Habit | Perennials; caudex simple or branched (not fleshy, usually with some persistent leaf remains); sometimes scapose. | Perennials; (cespitose); caudex branched (sometimes with persistent leaf remains); sometimes scapose. |
Stems | unbranched, (0.1–)0.3–0.9 dm, glabrous throughout or sparsely pubescent proximally, trichomes simple and 2–6-rayed, 0.1–0.5 mm. |
unbranched, 0.3–1.4 dm, pubescent throughout, trichomes simple, 0.2–1 mm, and 2–6-rayed, 0.05–0.3 mm. |
Basal leaves | rosulate; petiolate; petiole (0–0.5 cm), ciliate throughout; blade oblanceolate to obovate, 0.4–1.7(–2.3) cm × 1.6–4(–6) mm, margins usually entire, rarely denticulate, (sparsely ciliate, trichomes simple, 0.3–0.8 mm), surfaces pubescent, abaxially with stalked, (2–)4(–6)-rayed trichomes, (0.05–)0.1–0.6 mm, adaxially with simple and fewer, stalked, 2–4-rayed ones. |
rosulate; petiolate; petiole base and margin ciliate, (trichomes mostly simple, 0.2–1 mm); blade oblanceolate to narrowly obovate, 0.4–1.7 cm × 1.5–6 mm, margins entire or with 1–3 teeth on each side, surfaces pubescent with primarily simple trichomes, 0.3–1mm, abaxially mixed with stalked, 4–10-rayed ones, 0.1–0.2 mm. |
Cauline leaves | 0 or 1; sessile; blade ovate to lanceolate, margins entire, surfaces pubescent as basal. |
0 or 1; sessile; blade ovate to oblong, margins entire or toothed, surfaces pubescent as basal. |
Racemes | (2–)4–9(–12)-flowered, ebracteate, elongated in fruit; rachis slightly flexuous, glabrous. |
2–14(–17)-flowered, ebracteate, elongated in fruit; rachis not flexuous, pubescent as stem. |
Flowers | sepals ovate, 1.2–1.7 mm, pubescent, (trichomes simple and short-stalked, 2- or 3-rayed); petals yellowish (quickly fading white), spatulate, 1.8–2.2 × 0.6–1 mm; anthers ovate, 0.25–0.3 mm. |
sepals ovate, 1.8–2.5 mm, pubescent, (trichomes simple and short-stalked, 2–4-rayed); petals white, spatulate, 3–4 × 1.5–2 mm; anthers ovate, 0.3–0.4 mm. |
Fruiting pedicels | divaricate-ascending, straight, 2–5(–8) mm, glabrous. |
suberect to ascending, straight, 1–5(–7) mm, pubescent, trichomes simple and 2–4-rayed. |
Fruits | elliptic to linear lanceolate, plane, flattened, 5–10(–12) × 1.7–2(–2.5) mm; valves glabrous; ovules 20–30 per ovary; style 0.08–0.2 mm. |
oblong, plane, flattened, 4–9 × 2–3.5 mm; valves pubescent, trichomes short-stalked, 2–4-rayed, 0.1–0.5 mm, sometimes with simple ones; ovules 20–32 per ovary; style 0.1–0.4 mm (stigma distinctly wider than style). |
Seeds | oblong, 0.9–1.2 × 0.5–0.8 mm. |
ovoid, 0.7–1 × 0.5–0.6 mm. |
2n | = 40. |
= 48. |
Draba paucifructa |
Draba arctogena |
|
Phenology | Flowering Jun–Jul. | Flowering Jun–Jul. |
Habitat | Moist, shaded slopes among limestone and dolomite rocks | Scree, sandy hills, gravel flats |
Elevation | 2600-3500 m (8500-11500 ft) | 0-450 m (0-1500 ft) |
Distribution |
NV |
NT; NU; Greenland |
Discussion | Of conservation concern. Draba paucifructa is known from the Charleston Mountains in Clark County. M. D. Windham (2004) suggested that it is an allopolyploid resulting from hybridization between D. albertina and D. lonchocarpa, and he discussed the morphological features that distinguish this species from its putative parents. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Draba arctogena is sometimes confused with D. norvegica, from which it differs by having less elongated fruiting racemes, abaxial leaf surfaces with 4–10-rayed (versus cruciform or, rarely, 2–6-rayed) trichomes, and fruits with 2–4-rayed trichomes, 0.1–0.5 mm, (versus glabrous or with simple and 2–4-rayed trichomes, 0.05–0.25 mm). The limits of D. arctica, D. arctogena, D. cinerea, and D. oblongata need to be critically evaluated in light of molecular and cytological data. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 327. | FNA vol. 7, p. 292. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | D. groenlandica var. arctogena, D. cinerea var. arctogena | |
Name authority | Clokey & C. L. Hitchcock: Madroño 5: 127. (1939) | (E. Ekman) E. Ekman: Svensk Bot. Tidskr. 25: 492. (1932) |
Web links |