Draba incana |
Draba serpentina |
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twisted Draba |
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Habit | Biennials; not scapose. | Perennials; (cespitose); caudex branched (with persistent leaves, branches sometimes terminating in sterile rosettes); 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, 0.3–1.3 dm, glabrous throughout. |
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. |
rosulate; sessile; blade obovate to obovate-oblanceolate, 0.4–1 cm × (2–)2.5–4(–5) mm, margins entire, (ciliate, trichomes simple, 0.2–0.5 mm, apex acute), surfaces glabrous. |
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. |
Racemes | (11–)17–36(–48)-flowered, bracteate basally, elongated or not in fruit; rachis not flexuous, pubescent as stems distally. |
6–14-flowered, ebracteate, elongated in fruit; rachis not flexuous, glabrous. |
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, 2–3 mm, glabrous; petals white, spatulate to obovate, 5–6.5 × 2–3 mm; anthers ovate to oblong, 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, straight, 5–13 mm, glabrous. |
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. |
lanceolate to narrowly oblong, slightly twisted or plane, flattened, 6–12 × 2–3.5 mm; valves glabrous; ovules 8–16 per ovary; style 0.6–1.8(–2.5) mm. |
Seeds | oblong, 0.7–1.1 × 0.5–0.6 mm. |
oblong, 1.1–1.4 × 0.7–0.8 mm. |
2n | = 32. |
= 52. |
Draba incana |
Draba serpentina |
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Phenology | Flowering Jul–Aug. | Flowering May–Jul. |
Habitat | Rock outcrops, talus, gravelly shores | Rock outcrops, talus, and gravelly soil in mixed conifer and subalpine meadow communities |
Elevation | 0-200 m (0-700 ft) | 3200-3600 m (10500-11800 ft) |
Distribution |
MI; MN; MB; NB; NL; ON; PE; QC; Greenland; n Europe; c Europe (Russia) |
NV |
Discussion | Of conservation concern. Draba serpentina has been treated by other authors as a variety or synonym of D. oreibata. As indicated by I. A. Al-Shehbaz and M. D. Windham (2007), the two taxa are morphologically distinct, have different chromosome numbers, and are separated by over 480 kilometers. They are treated herein as separate species. Draba serpentina is known only from the Snake Range (White Pine County) and the Toiyabe Mountains (Lander County) in central Nevada. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Source | FNA vol. 7, p. 312. | FNA vol. 7, p. 335. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | D. confusa, D. contorta, D. incana subsp. confusa, D. incana var. confusa, D. incana var. contorta | D. oreibata var. serpentina |
Name authority | Linnaeus: Sp. Pl. 2: 643. (1753) | (Tiehm & P. K. Holmgren) Al-Shehbaz & Windham: Harvard Pap. Bot. 12: 414. (2007) |
Web links |