Draba incana |
Draba cana |
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twisted Draba |
Brewer's Draba, canescent Draba, canescent whitlow-mustard, cushion Draba, hoary Draba, hoary whitlow-grass, lance-leaf Draba, lance-leaf whitlow-grass |
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Habit | Biennials; not scapose. | Perennials; caudex simple or branched (branches short); not scapose. |
Stems | usually branched, rarely unbranched, (0.3–)0.6–3(–4) dm, densely pubescent proximally, trichomes simple, 0.4–1.3 mm, with fewer 2–4-rayed ones, to 0.3 mm, (distally with mostly branched trichomes, with fewer, simple ones). |
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). |
Basal leaves | rosulate; petiolate; petiole base and margin ciliate, (trichomes simple, 0.2–0.7 mm); blade lanceolate or oblanceolate to spatulate, 0.5–2.9 cm × 1–5(–9) mm, margins dentate, surfaces pubescent, abaxially with stalked, cruciform, or 2- or 3-rayed trichomes, 0.1–0.4 mm, (rarely with a branched ray), adaxially with simple trichomes, 0.1–0.7 mm, and stalked, 2–4-rayed ones. |
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. |
Cauline leaves | (15–)22–54(–76), (densely imbricate at least basally); sessile; blade ovate to oblong or lanceolate (base often densely bearded abaxially, trichomes simple, to 1.3 mm), margins dentate, surfaces pubescent as basal. |
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). |
Racemes | (11–)17–36(–48)-flowered, bracteate basally, elongated or not in fruit; rachis not flexuous, pubescent as stems distally. |
(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. |
Flowers | sepals ovate, 2–2.5 mm, pubescent, (trichomes simple and short-stalked, 2–4-rayed); petals white, spatulate, 3.5–4.5 × 1–2 mm; anthers ovate, 0.3–0.4 mm. |
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. |
Fruiting pedicels | erect to ascending, (subappressed to rachis), straight, (1.5–)2.5–6(–13) mm, pubescent, trichomes 2–4-rayed and simple. |
suberect or ascending, straight, 2–5(–10) mm, pubescent as rachis. |
Fruits | oblong to linear-lanceolate or elliptic, slightly twisted or plane, flattened, 5–10(–12) × 1.5–2.5(–3) mm; valves glabrous or pubescent, trichomes simple and short-stalked, 2–4-rayed, 0.05–0.3 mm; ovules (24–)30–40 per ovary; style 0.01–0.25 mm. |
(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. |
Seeds | oblong, 0.7–1.1 × 0.5–0.6 mm. |
ovoid, 0.5–0.7(–0.9) × 0.3–0.5 mm. |
2n | = 32. |
= 32. |
Draba incana |
Draba cana |
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Phenology | Flowering Jul–Aug. | Flowering (May-)Jun–Aug. |
Habitat | Rock outcrops, talus, gravelly shores | Rock outcrops and talus, open prairie benchlands, roadsides, meadows, alpine tundra |
Elevation | 0-200 m (0-700 ft) | 0-4100 m (0-13500 ft) |
Distribution |
MI; MN; MB; NB; NL; ON; PE; QC; Greenland; n Europe; c Europe (Russia) |
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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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.) |
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Source | FNA vol. 7, p. 312. | FNA vol. 7, p. 298. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | D. confusa, D. contorta, D. incana subsp. confusa, D. incana var. confusa, D. incana var. contorta | D. breweri var. cana, D. valida |
Name authority | Linnaeus: Sp. Pl. 2: 643. (1753) | Rydberg: Bull. Torrey Bot. Club 29: 241. (1902) |
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