Draba alpina |
Draba howellii |
|
---|---|---|
alpine Draba |
Howell's Draba, Howell's whitlow-grass, rosette Draba |
|
Habit | Perennials; (cespitose); caudex branched (covered with persistent leaves or leaf remains); scapose. | Perennials; (loosely cespitose); caudex branched (somewhat surculose, with persistent leaf remains, branches sometimes terminating in sterile rosettes); often scapose. |
Stems | unbranched, (0.3–)0.5–1.7(–2.8) dm, pubescent throughout, trichomes simple and 2-rayed, 0.3–0.8 mm, with 3–5-rayed ones, 0.1–0.3 mm. |
unbranched, (0.2–)0.4–1.1(–1.5) dm, usually pubescent throughout, rarely glabrous, trichomes simple and 2–4-rayed, 0.1–0.6 mm. |
Basal leaves | rosulate; petiolate; petiole base (not thickened), ciliate, (trichomes simple, 0.3–1 mm); blade oblanceolate to obovate or lanceolate to oblong, 0.8–3(–4.5) cm × 2.5–6(–9) mm, margins entire, surfaces abaxially pubescent with stalked, 2–4-rayed trichomes, 0.1–0.5 mm, with simple ones (midvein obscure, not thickened), adaxially glabrous or sparsely pubescent with simple and stalked, 2–4-rayed trichomes. |
rosulate; blade (somewhat fleshy), oblanceolate or spatulate to obovate, 0.4–1.6(–2.5) cm × (1.5–)3–6(–10) mm, margins entire, surfaces pubescent with stalked, cruciform, and fewer 2- or 3-rayed trichomes, 0.07–0.5 mm, rarely both surfaces glabrous and trichomes on margins, (midvein obscure abaxially). |
Cauline leaves | 0. |
0–3 (or 4); sessile; blade ovate to oblong, margins entire, pubescent as basal. |
Racemes | 6–18-flowered, ebracteate, considerably elongated in fruit; rachis not flexuous, pubescent as stem. |
(5–)7–18(–25)-flowered, usually ebracteate, sometimes proximalmost 1 or 2 flowers bracteate, elongated in fruit; rachis not flexuous, usually pubescent as stem, rarely glabrous. |
Flowers | sepals (purplish tinged), narrowly ovate, 2.5–3 mm, pubescent, (trichomes simple and fewer, stalked, 2-rayed); petals bright yellow, narrowly obovate, 3.5–5 × 1.7–2.5 mm; anthers ovate, 0.3–0.4 mm. |
sepals ovate, 2.5–3.2 mm, glabrous or pubescent, (trichomes 2–4-rayed); petals yellow, oblanceolate, 5.5–8 × 1–2 mm; anthers oblong, 0.7–0.9 mm. |
Fruiting pedicels | ascending to divaricate-ascending, straight or, sometimes, slightly curved upwards, 4–14(–30) mm, pubescent, trichomes simple and 2–4-rayed. |
divaricate-ascending, straight, (4–)7–10 mm, usually pubescent as stem, rarely glabrous. |
Fruits | elliptic, plane, flattened, 6–10 × 2–3 mm; valves glabrous or glabrescent, trichomes simple, (not confined to replum); ovules 12–24 per ovary; style 0.2–0.3 mm (stigma about as wide as style). |
lanceolate to elliptic-lanceolate or broadly ovate, plane (not curved), strongly flattened, 6–11(–15) × 3–5 mm; valves usually pubescent, rarely glabrous, trichomes simple and 2–4-rayed, 0.05–0.3 mm; ovules 8–22 per ovary; style (0.7–)1.6–3 mm. |
Seeds | (pale brown), ovoid, 0.9–1.3 × 0.6–0.9 mm. |
oblong, 1–1.6 × 0.8–1 mm, (sometimes distally appendaged). |
2n | = 80. |
|
Draba alpina |
Draba howellii |
|
Phenology | Flowering Jun–Aug. | Flowering Jul–Aug. |
Habitat | Moist tundra and ridges, sand and gravel flats or beaches | Rocky summits, cracks in granite walls, rock crevices |
Elevation | 0-1000 m (0-3300 ft) | 1900-2700 m (6200-8900 ft) |
Distribution |
LB; MB; NU; ON; QC; Greenland; Europe (Finland, Norway, Russia, Sweden)
|
CA; OR |
Discussion | The synonymy above includes two North American names overlooked by C. L. Hitchcock (1941) and R. C. Rollins (1993). Draba alpina was broadly delimited by O. E. Schulz (1927) and included 17 varieties, some of which (e.g., corymbosa, oxycarpa, pilosa) are recognized herein as distinct species. The name D. alpina was so misapplied that it was used for any circumpolar or alpine, scapose, yellow-flowered, perennial Draba. Various chromosome numbers (e.g., 2n = 64, 80, 112, 120; S. I. Warwick and I. A. Al-Shehbaz 2006) have been reported for the species. As circumscribed here, it has the narrow distribution outlined above and includes plants with 2n = 80. Reports of the species from Alaska, Canadian Northwest Territories and Yukon, Siberia, eastern Asia, Russian Far East, and the Central Asian republics are either suspect or very unlikely. The entire D. alpina complex (including the above three species, D. glacialis Adams, D. macounii, etc.) is in need of critical molecular, cytological, and morphological study. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Draba howellii is known from Siskiyou and Trinity counties, California, and Josephine County, Oregon. One collection, Tracy 14623 (DS, GH, UC), is unusual in having glabrous stems, pedicels, and leaf blade surfaces. In this regard, it resembles D. carnosula, but in all other respects (bracts, seeds, inflorescences, etc.), it is indistinguishable from D. howellii. For characteristics distinguishing the two species, see 23. D. carnosula. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 290. | FNA vol. 7, p. 312. |
Parent taxa | Brassicaceae > tribe Arabideae > Draba | Brassicaceae > tribe Arabideae > Draba |
Sibling taxa | ||
Synonyms | D. alpina var. hydeana, D. alpina var. inflatisiliqua | |
Name authority | Linnaeus: Sp. Pl. 2: 642. (1753) | S. Watson: Proc. Amer. Acad. Arts 20: 354. (1885) |
Web links |