Draba alpina |
Draba juvenilis |
|
---|---|---|
alpine Draba |
long-stalk Draba, long-stalk whitlow-grass |
|
Habit | Perennials; (cespitose); caudex branched (covered with persistent leaves or leaf remains); scapose. | Perennials; (not pulvinate); caudex branched (branches slightly loose, with persistent leaf remains, 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, (0.3–)0.8–2.3(–3) dm, pubescent proximally, glabrous or sparsely pubescent distally, trichomes simple and 2–4-rayed, 0.07–0.4 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. |
(loosely) rosulate; petiolate; petiole base ciliate, margin not ciliate, (midvein obscure, trichomes simple and 2-rayed, 0.2–0.7 mm); blade oblanceolate to lanceolate, (0.3–)0.6–2.5(–3.5) cm × (1–)2–7(–10) mm, margins entire or denticulate, surfaces pubescent, abaxially with stalked, cruciform trichomes, 0.2–0.5 mm, adaxially with cruciform and/or simple and 2-rayed ones. |
Cauline leaves | 0. |
0–2 (or 3); sessile; blade elliptic to ovate or lanceolate, margins usually entire, rarely denticulate, surfaces pubescent as basal adaxially or trichomes predominantly simple. |
Racemes | 6–18-flowered, ebracteate, considerably elongated in fruit; rachis not flexuous, pubescent as stem. |
(2–)4–13(–18)-flowered, ebracteate, elongated in fruit; rachis not flexuous, glabrous or sparsely pubescent as stem. |
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, 2.2–3 mm, glabrous or pubescent subapically, (trichomes simple and short-stalked, 2-rayed); petals pale yellow to creamy white, spatulate, 3–5 × 1.5–2.5 mm; anthers ovate, 0.4–0.5 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 or ascending, straight or often curved upward (not expanded basally), (3–)5–17(–22) mm, usually glabrous, rarely pubescent, trichomes simple and stalked, 2–4-rayed. |
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). |
elliptic to oblong or linear-lanceolate, plane (not curved), flattened, 5–11(14) × 2–3 mm; valves usually glabrous, rarely margin pubescent, trichomes simple; ovules 16–30 per ovary; style 0.2–0.7 mm. |
Seeds | (pale brown), ovoid, 0.9–1.3 × 0.6–0.9 mm. |
oblong, 0.7–1.2(–1.5) × 0.4–0.7(–0.8) mm. |
2n | = 80. |
= 64. |
Draba alpina |
Draba juvenilis |
|
Phenology | Flowering Jun–Aug. | Flowering Jun–Jul. |
Habitat | Moist tundra and ridges, sand and gravel flats or beaches | Rock outcrops, talus, gravelly beaches and stream banks, meadows, tundra |
Elevation | 0-1000 m (0-3300 ft) | 0-2700 m (0-8900 ft) |
Distribution |
LB; MB; NU; ON; QC; Greenland; Europe (Finland, Norway, Russia, Sweden)
|
AK; AB; BC; NT; YT; e Asia (Russian Far East, n Siberia) |
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.) |
Although Draba kananaskis and D. longipes have often been treated as distinct species, we find no basis for maintaining them. Both exhibit variations in petal color (white to pale yellow) and leaf trichomes (short-stalked to sessile) characteristic of D. juvenilis from the Russian Far East. Perhaps most importantly, all three are octoploids (2n = 64) with x = 8. We conclude that D. kananaskis is nothing more than a minor variant of D. juvenilis and it is treated herein, for the first time, as a synonym of that species. Draba juvenilis is occasionally confused with D. borealis, which also has stalked, cruciform trichomes with unbranched rays. Typical D. juvenilis is easily distinguished from that species by having narrower (2–3 mm) fruits that are glabrous (rarely pubescent) and untwisted, and 0–2 (or 3)-leaved stems. By contrast, D. borealis has wider (2.5–4.5 mm) fruits that are usually pubescent and/or twisted (rarely neither) and (2 or) 3–7(–12)-leaved stems. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 290. | FNA vol. 7, p. 314. |
Parent taxa | Brassicaceae > tribe Arabideae > Draba | Brassicaceae > tribe Arabideae > Draba |
Sibling taxa | ||
Synonyms | D. alpina var. hydeana, D. alpina var. inflatisiliqua | D. hirta var. tenella, D. kananaskis, D. longipes |
Name authority | Linnaeus: Sp. Pl. 2: 642. (1753) | Komarov: Repert. Spec. Nov. Regni Veg. 13: 167. (1914) |
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