Draba cana |
Draba sierrae |
|
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Brewer's Draba, canescent Draba, canescent whitlow-mustard, cushion Draba, hoary Draba, hoary whitlow-grass, lance-leaf Draba, lance-leaf whitlow-grass |
Sierra Draba |
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Habit | Perennials; caudex simple or branched (branches short); not scapose. | Perennials; (cespitose, pulvinate, canescent); caudex branched (covered with persistent leaves, branches sometimes terminating in sterile rosettes); scapose. |
Stems | unbranched or branched distally, (0.6–)1–3(–3.8) dm, pubescent throughout, trichomes simple, 0.5–1mm, with 4–10-rayed ones, 0.05–0.2 mm (mostly branched on basal parts). |
unbranched, (0.05–)0.1–0.4 dm, pubescent throughout, trichomes pectinate or 2–4-rayed, 0.1–0.4 mm, and sometimes simple. |
Basal leaves | rosulate; petiolate; petiole ciliate throughout; blade linear to oblanceolate or oblong, (0.5–)0.8–2(–3.5) cm × 1.5–4(–11) mm, margins entire or dentate, (base and apex ciliate, trichomes simple, 0.3–0.8 mm), surfaces pubescent with short-stalked, 4–12-rayed trichomes, 0.1–0.3 mm. |
(densely imbricate); rosulate; sessile; blade oblong, 0.2–0.6(–0.8) cm × 0.7–1.5(–2) mm, margins entire, (sometimes ciliate, trichomes simple, 0.5–1 mm), surfaces densely pubescent with stalked, subdendritic, 7–12-rayed trichomes, 0.2–0.5 mm. |
Cauline leaves | 3–10(–17), (not overlapping); sessile; blade lanceolate to ovate or oblong, margins entire or dentate, surfaces pubescent as basal (adaxially with simple and forked trichomes near blade base). |
0. |
Racemes | (10–)15–47(–63)-flowered, basally bracteate, often considerably elongated in fruit; rachis not flexuous, densely pubescent, trichomes 4–10-rayed (0.05–0.2 mm), and fewer simple ones. |
2–6(–9)-flowered, ebracteate, elongated in fruit; rachis not flexuous, pubescent as stem. |
Flowers | sepals (green or lavender), oblong to ovate, 1.5–2 mm, pubescent, (trichomes simple and few-rayed); petals white, oblanceolate to spatulate, 2.3–3.7(–4.5) × 0.7–1.7 mm; anthers ovate, 0.1–0.2 mm. |
sepals oblong, 2.5–3.5 mm, pubescent, (trichomes short-stalked, branched); petals yellow, spatulate, 4–5 × 1.2–1.8 mm; anthers oblong, 0.5–0.7 mm. |
Fruiting pedicels | suberect or ascending, straight, 2–5(–10) mm, pubescent as rachis. |
divaricate to ascending, straight, 2–5(–7) mm, pubescent as stem. |
Fruits | (subappressed to rachis), linear-lanceolate to linear or, rarely, ovate-oblong, slightly twisted or plane, flattened, (5–)6–11 × 1.5–2(–2.5) mm; valves pubescent, trichomes short-stalked, 3–7-rayed, 0.05–0.3 mm; ovules 28–48 per ovary; style 0.1–0.6 mm. |
lanceolate to elliptic or broadly oblong to ovate-orbicular, often twisted, occasionally plane, flattened, 4–8(–10) × (2–)3–4.5 mm (asymmetric); valves pubescent, trichomes short-stalked, subpectinate, or 2–4-rayed, 0.05–0.3 mm, sometimes with simple ones; ovules 8–14(–16) per ovary; style (0.1–)0.3–0.7(–1) mm. |
Seeds | ovoid, 0.5–0.7(–0.9) × 0.3–0.5 mm. |
ovoid, 1.2–1.5 × 0.7–1 mm. |
2n | = 32. |
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Draba cana |
Draba sierrae |
|
Phenology | Flowering (May-)Jun–Aug. | Flowering Jun–Aug. |
Habitat | Rock outcrops and talus, open prairie benchlands, roadsides, meadows, alpine tundra | Granite outcrops, rocky slopes |
Elevation | 0-4100 m (0-13500 ft) | 3500-3900 m (11500-12800 ft) |
Distribution |
AK; CA; CO; ID; ME; MI; MT; NH; NM; NV; SD; UT; VT; WA; WI; WY; AB; BC; MB; NB; NF; NT; ON; QC; SK; YT; Greenland
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CA |
Discussion | The limits of Draba cana have long been confused, and the species was treated as a synonym of the Himalayan D. lanceolata Royle (M. L. Fernald 1934; C. L. Hitchcock 1941) or as a variety of the western North American D. breweri (R. C. Rollins 1993). However, G. A. Mulligan (1971) clearly demonstrated that all three are distinct and should be maintained. Some Utah plants corresponding to the type of D. valida have shorter and wider oblong-ovate fruits. In all other aspects, they are indistinguishable from D. cana. Additional studies are needed to establish whether such plants should be formally recognized. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Of conservation concern. Draba sierrae is known only from the southern Sierra Nevada in east-central California (Inyo and Fresno counties). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 298. | FNA vol. 7, p. 337. |
Parent taxa | Brassicaceae > tribe Arabideae > Draba | Brassicaceae > tribe Arabideae > Draba |
Sibling taxa | ||
Synonyms | D. breweri var. cana, D. valida | |
Name authority | Rydberg: Bull. Torrey Bot. Club 29: 241. (1902) | Sharsmith: Madroño 5: 149. (1940) |
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