Draba albertina |
Draba arctogena |
|
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Alaska Draba, Alaska whitlow-grass, Alberta whitlow grass, slender Draba, slender whitlow-grass |
fellfield whitlowgrass |
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Habit | Annuals, biennials, or perennials; caudex (or base) simple or branched (poorly developed); rarely scapose. | Perennials; (cespitose); caudex branched (sometimes with persistent leaf remains); sometimes scapose. |
Stems | branched distally, (0.3–)0.5–3(–4.2) dm, pubescent proximally, often glabrous distally, trichomes simple, 0.1–1 mm, sometimes with fewer, stalked, 2-rayed ones. |
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; shortly petiolate; petiole (0–0.5 cm), ciliate throughout; blade obovate to oblanceolate or linear-lanceolate, (0.3–)1–2.8(–3.5) cm × (1–)2–6(–9) mm, margins entire or denticulate, (ciliate, trichomes simple, 0.4–1 mm), surfaces usually pubescent, abaxially with stalked, 2–4-rayed trichomes, 0.05–0.4(–0.5) mm, (rarely with simple trichomes along midvein), adaxially with simple trichomes sometimes also with 2-rayed ones, 0.07–0.4 mm, rarely glabrous. |
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) 1–3(–5); sessile; blade lanceolate to elliptic or ovate, margins entire or denticulate, surfaces pubescent as basal. |
0 or 1; sessile; blade ovate to oblong, margins entire or toothed, surfaces pubescent as basal. |
Racemes | (2–)6–30(–50)-flowered, ebracteate, elongated in fruit; rachis straight or, rarely, flexuous, glabrous. |
2–14(–17)-flowered, ebracteate, elongated in fruit; rachis not flexuous, pubescent as stem. |
Flowers | (chasmogamous, petaliferous); sepals ovate, 1.4–2.1 mm, glabrous or sparsely pubescent, (trichomes simple); petals yellow, spatulate to oblanceolate, 2–3.2 × 0.7–1.2 mm; anthers ovate, 0.15–0.25 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 or horizontal, (not appressed to rachis), usually straight, rarely curved upward, (3–)5–14(–16) mm (subequaling or shorter than fruit), usually glabrous, rarely sparsely puberulent. |
suberect to ascending, straight, 1–5(–7) mm, pubescent, trichomes simple and 2–4-rayed. |
Fruits | lanceolate to narrowly elliptic or linear, plane, flattened, (4–)6–12(–15) × (1–)1.4–2.1 mm; valves glabrous; ovules (20–)24–38(–44) per ovary; style 0.01–0.12 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, 0.7–1 × 0.4–0.5 mm. |
ovoid, 0.7–1 × 0.5–0.6 mm. |
2n | = 24. |
= 48. |
Draba albertina |
Draba arctogena |
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Phenology | Flowering Jun–Aug. | Flowering Jun–Jul. |
Habitat | Open woodlands, pine forests, meadows, rocky knolls, alpine slopes, stream banks, disturbed areas | Scree, sandy hills, gravel flats |
Elevation | 900-3700 m (3000-12100 ft) | 0-450 m (0-1500 ft) |
Distribution |
AK; AZ; CA; CO; ID; MT; NM; NV; OR; UT; WA; WY; AB; BC; NT; YT
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NT; NU; Greenland |
Discussion | O. E. Schulz (1927) and C. L. Hitchcock (1941) confused the limits of Draba albertina, D. crassifolia, and D. stenoloba; the latter author treated the first two species as conspecific. G. A. Mulligan (1975) demonstrated that the three taxa are chromosomally and morphologically distinct (see D. crassifolia and D. stenoloba for differences from D. albertina). The ranges of D. albertina and D. crassifolia overlap extensively, and occasional sterile hybrids are encountered. The Alaskan record of Draba albertina is based on Minard 4 (ALA), collected on the northern coast of Afognak Island (58°22’N, 152°28’W). The record from New Mexico is based on O’Kane & Hedin 3871 (ISTC, SJC), collected in Chuska Mountains (36°8’11”N, 108°54’19”W). (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. 288. | FNA vol. 7, p. 292. |
Parent taxa | Brassicaceae > tribe Arabideae > Draba | Brassicaceae > tribe Arabideae > Draba |
Sibling taxa | ||
Synonyms | D. crassifolia var. albertina, D. crassifolia var. nevadensis, D. deflexa, D. nitida, D. nitida var. nana, D. stenoloba var. nana, D. stenoloba var. ramosa | D. groenlandica var. arctogena, D. cinerea var. arctogena |
Name authority | Greene: Pittonia 4: 312. (1901) | (E. Ekman) E. Ekman: Svensk Bot. Tidskr. 25: 492. (1932) |
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