Draba juvenilis |
Draba yukonensis |
|
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long-stalk Draba, long-stalk whitlow-grass |
Yukon whitlowgrass |
|
Habit | Perennials; (not pulvinate); caudex branched (branches slightly loose, with persistent leaf remains, sometimes terminating in sterile rosettes); often scapose. | Perennials; (short-lived); caudex simple or branched (with persistent leaf remains); not scapose. |
Stems | 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. |
branched, 0.4–2 dm, pubescent throughout, trichomes simple, 0.3–1.2 mm, and 2–6-rayed, 0.05–0.6 mm. |
Basal leaves | (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. |
rosulate; subsessile; blade oblanceolate to narrowly so, 0.3–1 cm × 0.5–2 mm, margins entire, (ciliate, trichomes simple, to 1.3 mm), surfaces pubescent, abaxially with (rigid), simple and 2-rayed trichomes, 0.4–1.2 mm, sometimes with short-stalked, 3–6-rayed ones, 0.1–0.3 mm, adaxially with simple trichomes. |
Cauline leaves | 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. |
1–3; sessile; blade ovate to oblong, margins entire, surfaces pubescent as basal. |
Racemes | (2–)4–13(–18)-flowered, ebracteate, elongated in fruit; rachis not flexuous, glabrous or sparsely pubescent as stem. |
5–20-flowered, ebracteate, considerably elongated in fruit; rachis not flexuous, pubescent as stem. |
Flowers | 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. |
sepals ovate, 1.2–1.6 mm, pubescent, (trichomes simple and 2–4-rayed); petals white, spatulate, 1.5–2 × 0.7–0.8 mm; anthers ovate, ca. 0.2 mm. |
Fruiting pedicels | 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. |
erect to ascending, straight, 0.5–3 mm, pubescent as stem. |
Fruits | 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. |
ovoid to oblong, plane, not flattened, 2–5 × 1.5–2 mm; valves pubescent, trichomes short-stalked, 4- or 5-rayed, 0.05–0.3 mm; ovules 36–52 per ovary; style 0.1–0.3 mm. |
Seeds | oblong, 0.7–1.2(–1.5) × 0.4–0.7(–0.8) mm. |
oblong, 0.6–0.8 × 0.3–0.4 mm. |
2n | = 64. |
|
Draba juvenilis |
Draba yukonensis |
|
Phenology | Flowering Jun–Jul. | Flowering late May–Jun. |
Habitat | Rock outcrops, talus, gravelly beaches and stream banks, meadows, tundra | Open stony ridges on ancient beach in grassy areas and aspen stands |
Elevation | 0-2700 m (0-8900 ft) | ca. 600 m (ca. 2000 ft) |
Distribution |
AK; AB; BC; NT; YT; e Asia (Russian Far East, n Siberia) |
YT |
Discussion | 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.) |
Of conservation concern. Draba yukonensis is known only from Kluane National Park, southwestern Yukon Territory. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 314. | FNA vol. 7, p. 346. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | D. hirta var. tenella, D. kananaskis, D. longipes | |
Name authority | Komarov: Repert. Spec. Nov. Regni Veg. 13: 167. (1914) | A. E. Porsild: Publ. Bot. (Ottawa) 4: 37, plate 7. (1975) |
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