Draba albertina |
Draba arctica |
|
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Alaska Draba, Alaska whitlow-grass, Alberta whitlow grass, slender Draba, slender whitlow-grass |
arctic whitlowgrass |
|
Habit | Annuals, biennials, or perennials; caudex (or base) simple or branched (poorly developed); rarely scapose. | Perennials; (cespitose, not pulvinate); caudex simple or branched; rarely 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, 0.3–1.7(–2.4) dm, pubescent, trichomes 4–10-rayed (rays sometimes branched), 0.1–0.3 mm, with fewer, simple ones, to 0.7 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 ciliate, (trichomes simple, 0.2–0.8 mm); blade oblanceolate to narrowly obovate, 0.4–2.3(–3) cm × 1.5–6.5 mm, margins usually entire, rarely with 1 tooth on each side, surfaces densely pubescent with minutely stalked, 8–12-rayed, stellate trichomes, 0.2–0.4 mm, sometimes with coarser, simple or 2-rayed ones, (midvein distinct abaxially). |
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(–3); sessile; blade ovate or oblong to lanceolate, margins entire, surfaces pubescent as basal. |
Racemes | (2–)6–30(–50)-flowered, ebracteate, elongated in fruit; rachis straight or, rarely, flexuous, glabrous. |
3–18(–25)-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, 2–2.5 mm, pubescent, (trichomes short-stalked, 2- or 3-rayed, and simple); petals white, spatulate to obovate, 3.5–6 × 1.8–2 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. |
divaricate-ascending or ascending, straight, (1.5–)2–6 mm, pubescent, trichomes stalked, stellate, and, sometimes, simple. |
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 to lanceolate, plane, slightly flattened, (5–)6–11 × 2–3 mm; valves pubescent, trichomes short-stalked, 2–5-rayed (some rays branched), 0.05–0.3 mm; ovules 20–32 per ovary; style 0.1–1 mm (stigma distinctly wider than style). |
Seeds | oblong, 0.7–1 × 0.4–0.5 mm. |
ovoid, 0.8–1.1 × (0.6–)0.7–0.8 mm. |
2n | = 24. |
= 80. |
Draba albertina |
Draba arctica |
|
Phenology | Flowering Jun–Aug. | Flowering Jun–Jul. |
Habitat | Open woodlands, pine forests, meadows, rocky knolls, alpine slopes, stream banks, disturbed areas | Clay flats, gravel, beaches, limestone outcrops, talus |
Elevation | 900-3700 m (3000-12100 ft) | 0-500 m (0-1600 ft) |
Distribution |
AK; AZ; CA; CO; ID; MT; NM; NV; OR; UT; WA; WY; AB; BC; NT; YT
|
NU; Greenland; Europe (Norway [Svalbard]) |
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.) |
As circumscribed here, Draba arctica consists of two distinct elements often recognized as subspecies (arctica and ostenfeldii; T. W. Böcher 1966); perhaps they are better treated as distinct species (D. arctica and D. ovibovina). Lack of adequate material and inability to examine all of the types in this complex prevent us from doing so. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 288. | FNA vol. 7, p. 291. |
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. arctica subsp. ostenfeldii, D. arctica var. ostenfeldii, D. cinerea var. arctica, D. ostenfeldii, D. ostenfeldii var. ovibovina, D. ovibovina |
Name authority | Greene: Pittonia 4: 312. (1901) | J. Vahl: in G. C. Oeder et al., Fl. Dan. 13(39): plate 5, 2294. (1840) |
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