Draba incana |
Draba juvenilis |
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twisted Draba |
long-stalk Draba, long-stalk whitlow-grass |
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Habit | Biennials; not scapose. | Perennials; (not pulvinate); caudex branched (branches slightly loose, with persistent leaf remains, sometimes terminating in sterile rosettes); often scapose. |
Stems | usually branched, rarely unbranched, (0.3–)0.6–3(–4) dm, densely pubescent proximally, trichomes simple, 0.4–1.3 mm, with fewer 2–4-rayed ones, to 0.3 mm, (distally with mostly branched trichomes, with fewer, simple ones). |
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 and margin ciliate, (trichomes simple, 0.2–0.7 mm); blade lanceolate or oblanceolate to spatulate, 0.5–2.9 cm × 1–5(–9) mm, margins dentate, surfaces pubescent, abaxially with stalked, cruciform, or 2- or 3-rayed trichomes, 0.1–0.4 mm, (rarely with a branched ray), adaxially with simple trichomes, 0.1–0.7 mm, and stalked, 2–4-rayed ones. |
(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 | (15–)22–54(–76), (densely imbricate at least basally); sessile; blade ovate to oblong or lanceolate (base often densely bearded abaxially, trichomes simple, to 1.3 mm), margins dentate, surfaces pubescent as basal. |
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 | (11–)17–36(–48)-flowered, bracteate basally, elongated or not in fruit; rachis not flexuous, pubescent as stems distally. |
(2–)4–13(–18)-flowered, ebracteate, elongated in fruit; rachis not flexuous, glabrous or sparsely pubescent as stem. |
Flowers | sepals ovate, 2–2.5 mm, pubescent, (trichomes simple and short-stalked, 2–4-rayed); petals white, spatulate, 3.5–4.5 × 1–2 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 | erect to ascending, (subappressed to rachis), straight, (1.5–)2.5–6(–13) mm, pubescent, trichomes 2–4-rayed and simple. |
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 | oblong to linear-lanceolate or elliptic, slightly twisted or plane, flattened, 5–10(–12) × 1.5–2.5(–3) mm; valves glabrous or pubescent, trichomes simple and short-stalked, 2–4-rayed, 0.05–0.3 mm; ovules (24–)30–40 per ovary; style 0.01–0.25 mm. |
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 | oblong, 0.7–1.1 × 0.5–0.6 mm. |
oblong, 0.7–1.2(–1.5) × 0.4–0.7(–0.8) mm. |
2n | = 32. |
= 64. |
Draba incana |
Draba juvenilis |
|
Phenology | Flowering Jul–Aug. | Flowering Jun–Jul. |
Habitat | Rock outcrops, talus, gravelly shores | Rock outcrops, talus, gravelly beaches and stream banks, meadows, tundra |
Elevation | 0-200 m (0-700 ft) | 0-2700 m (0-8900 ft) |
Distribution |
MI; MN; MB; NB; NL; ON; PE; QC; Greenland; n Europe; c Europe (Russia) |
AK; AB; BC; NT; YT; e Asia (Russian Far East, n Siberia) |
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.) |
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Source | FNA vol. 7, p. 312. | FNA vol. 7, p. 314. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | D. confusa, D. contorta, D. incana subsp. confusa, D. incana var. confusa, D. incana var. contorta | D. hirta var. tenella, D. kananaskis, D. longipes |
Name authority | Linnaeus: Sp. Pl. 2: 643. (1753) | Komarov: Repert. Spec. Nov. Regni Veg. 13: 167. (1914) |
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