Draba oligosperma |
Draba mulliganii |
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few-seed Draba, few-seed Draba whitlow-grass, few-seed whitlow-grass |
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Habit | Perennials; (cespitose, densely pulvinate); caudex branched (with persistent leaf bases, branches congested or somewhat creeping, sometimes terminating in sterile rosettes); scapose. | Perennials; (cespitose); caudex branched (with persistent leaves); often scapose. |
Stems | unbranched, (0.1–)0.2–0.6(–1) dm, glabrous throughout or pubescent, trichomes sessile, pectinate, 0.1–0.3 mm, (their length parallel to long axis of stem). |
unbranched, 0.3–1.2 dm, glabrous throughout or sparsely pubescent proximally, trichomes short-stalked, 4–10-rayed, (non-crisped). |
Basal leaves | rosulate; sessile; blade linear to linear-oblanceolate, (0.2–)0.4–1.1(–1.5) cm × 0.4–1.5(–1.8) mm, margins entire, (not or, rarely, ciliate, trichomes simple, 0.2–0.4 mm), surfaces pubescent with sessile, pectinate trichomes, 0.1–0.4 mm, (their long axis parallel to prominent abaxial midvein), sometimes glabrous adaxially. |
rosulate; subsessile or shortly petiolate (petiolar base and proximal margin ciliate with stiff, subsetiform, simple trichomes, 0.3–0.6 mm); blade oblanceolate or lanceolate, 5–9 × 1–2 mm, margins entire, surfaces usually pubescent, abaxially with short-stalked, 8–12-rayed, stellate, (non-crisped) trichomes, 0.1–0.3 mm (often without spurred rays), rarely glabrescent, trichomes confined to margin, (midvein and petiole not thickened), adaxially with similar stellate and some simple trichomes. |
Cauline leaves | 0. |
0. |
Racemes | 4–12(–17)-flowered, ebracteate, elongated in fruit; rachis not flexuous, glabrous or pubescent as stem. |
3–11-flowered, ebracteate, elongated in fruit; rachis not flexuous, glabrous. |
Flowers | sepals ovate, 1.5–3 mm, glabrous or sparsely pubescent, (trichomes pectinate, 2-rayed, or simple); petals usually yellow, rarely creamy white, obovate, 2.5–4 × 1.5–3 mm; anthers ovate, 0.4–0.5 mm, (not producing pollen). |
sepals (caducous), ovate, 1.7–2.2 mm, pubescent subapically, (trichomes simple and 2-rayed); petals white, broadly obovate, 3.2–4 × 2–3 mm, (apex obtuse); anthers ovate, 0.4 mm. |
Fruiting pedicels | divaricate-ascending, straight, (2–)3–10(–13) mm, glabrous or sparsely pubescent, trichomes pectinate. |
divaricate to ascending (not appressed to rachis), straight, (4–)5–9 mm, glabrous. |
Fruits | ovoid to lanceolate, plane, inflated at least basally, sometimes slightly flattened distally, 3–6(–7) × 2–3.5(–4) mm; valves usually puberulent, rarely glabrous, trichomes simple and sessile, often unequally 2-rayed, 0.07–0.35 mm; ovules 6–12 per ovary; style 0.1–0.8(–1.1) mm. |
ovate-lanceolate to oblong, not twisted, flattened, 5–8 × 2–2.5 mm; valves glabrous; ovules 12–16 per ovary; style 0.4 1 mm. |
Seeds | ovoid, 1.1–1.5 × 0.7–1 mm. |
ovoid, 0.7–1.1 × 0.5–0.6 mm. |
2n | = 32, 64. |
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Draba oligosperma |
Draba mulliganii |
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Phenology | Flowering May–Jul. | Flowering Jun–Jul. |
Habitat | Rock outcrops, talus, gravel benches, tundra | Limestone gravel around outcrops, limestone crevices, dry serpentine knolls in heath vegetation with patches of exposed slide rock, shale rubble slopes |
Elevation | 200-3900 m (700-12800 ft) | 300-1600 m (1000-5200 ft) |
Distribution |
AK; CA; CO; ID; MT; NV; OR; WY; AB; BC; NT; NU; YT
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AK |
Discussion | Draba oligosperma is a highly variable and widespread species that has been shown to be apomictic (G. A. Mulligan and J. N. Findlay 1970; Mulligan 1972). It has been divided into species and infraspecific taxa by previous authors; the variation is continuous in every character; there are no clear geographical and morphological patterns that support its division. For characteristics separating D. oligosperma from the closely related D. pectinipila, see 80. D. pectinipila. Draba andina (Nuttall) A. Nelson (1899), not Philippi (1858) is an illegitimate name, sometimes found in synonymy under D. oligosperma. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Source | FNA vol. 7, p. 324. | FNA vol. 7, p. 321. |
Parent taxa | Brassicaceae > tribe Arabideae > Draba | Brassicaceae > tribe Arabideae > Draba |
Sibling taxa | ||
Synonyms | D. calcifuga, D. oligosperma var. andina, D. oligosperma var. leiocarpa, D. oligosperma var. microcarpa, D. oligosperma var. saximontana, D. oligosperma subsp. subsessilis, D. oligosperma var. subsessilis, D. saximontana, D. subsessilis | |
Name authority | Hooker: Fl. Bor.-Amer. 1: 51. (1830) | Al-Shehbaz: Harvard Pap. Bot. 14: 85. (2009) |
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