Draba aureola |
Draba porsildii |
|
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alpine whitlow-grass, golden alpine Draba, golden Draba, great alpine whitlow-grass, Mt. Lassen Draba, Mt. Lassen Draba whitlow-grass, Mt. Lassen whitlow-grass |
Porsild's Draba, Porsild's whitlow-grass |
|
Habit | Perennials; (short-lived); caudex simple or branched (poorly developed, with persistent dry leaves); not scapose. | Perennials; (cespitose); caudex branched (with persistent leaf remains); often scapose. |
Stems | unbranched or branched, 0.3–1.5 dm, hirsute throughout, trichomes simple and long-stalked, 2–4-rayed, 0.2–1.5 mm. |
unbranched, 0.2–1.2 dm, sparsely pubescent proximally, trichomes short-stalked, 3–5- rayed, (non-crisped), 0.2–0.4 mm, glabrous distally. |
Basal leaves | (forming dense clusters); rosulate; sessile; blade oblanceolate to linear, (0.7–)1–2.5(–3.2) cm × 2–3.5(–5) mm, margins entire, (ciliate, trichomes simple and 2-rayed, 0.5–1.5 mm), surfaces densely hirsute, abaxially with stalked, 3–5-rayed trichomes, 0.1–0.5 mm, adaxially with simple and long-stalked, 2-rayed trichomes, to 1 mm, with smaller, 3–5-rayed ones. |
rosulate; subsessile or shortly petiolate; petiole base and margin ciliate proximally, (trichomes simple, subsetiform, stiff, 0.3–0.9 mm); blade oblanceolate to obovate, 0.4–1.5 cm × 1–3 mm, margins entire, surfaces pubescent, abaxially with stalked, 6–12-rayed, (non-crisped) trichomes, 0.2–0.5 mm, (midvein obscure), adaxially similar, or with simple trichomes on proximal 1/2. |
Cauline leaves | 5–33; sessile; blade oblong to linear, margins entire, surfaces pubescent as basal. |
0 or 1; sessile; blade oblong to lanceolate, margins entire, surfaces pubescent as basal. |
Racemes | 12–83-flowered, ebracteate or proximalmost 1–9 flowers bracteate, slightly or not elongated in fruit; rachis not flexuous, hirsute as stem. |
3–13-flowered, ebracteate, elongated in fruit; rachis not flexuous, glabrous. |
Flowers | sepals ovate, 2.5–4 mm, glabrous; petals bright yellow, linear to linear-oblanceolate, 4–6 × 0.5–1(–1.2) mm; anthers narrowly oblong, 0.8–1 mm. |
sepals ovate, 1.5–2 mm, pubescent, (trichomes simple and 2-rayed); petals white, spatulate, 2–4 × 1–1.7 mm; anthers ovate, ca. 0.2 mm. |
Fruiting pedicels | horizontal to divaricate, usually straight, rarely curved upward, (3–)5–12(–19) mm, hirsute as stem. |
divaricate-ascending, straight, 1–4(–8) mm, glabrous. |
Fruits | oblong or, rarely, oblong-ovate, plane, flattened, (6–)9–14(–16) × 3–5 mm; valves pubescent, trichomes stalked, 2–4-rayed, 0.07–0.5 mm; ovules 10–20 per ovary; style (0.6–)1–1.6(–2) mm. |
ovate to oblong, plane, flattened, 4–7.5 × 1.7–3 mm; valves glabrous; ovules 12–16 per ovary; style 0.1–0.3(–0.5) mm. |
Seeds | oblong, 1.4–1.9 × 0.8–1.1 mm. |
ovoid, 0.7–1 × 0.5–0.6 mm. |
2n | = 20. |
= 32. |
Draba aureola |
Draba porsildii |
|
Phenology | Flowering Jul–Aug. | Flowering Jun–Jul. |
Habitat | Open conifer forests, alpine meadows and moraines, talus slopes | Rock outcrops, talus, meadows, gravel slopes |
Elevation | 2200-3200 m (7200-10500 ft) | 600-3000 m (2000-9800 ft) |
Distribution |
CA; OR; WA
|
AK; MT; WY; AB; YT |
Discussion | Draba aureola is known from Lassen, Shasta, and Siskiyou counties in California, Deschutes County in Oregon, and Lewis and Pierce counties in Washington. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
According to H. H. Grundt et al. (2004), tetraploid Draba porsildii probably originated from a diploid ancestor such as D. lonchocarpa. The Wyoming plants are a close match to the type of the species, though they have distinctly shorter pedicels. Some of the Alaskan plants are more problematic; they have finer and more branched trichomes, larger flowers, longer pedicels, and longer styles than the type. It is likely that they belong to another species; detailed molecular and cytological studies on this complex are needed before any meaningful conclusions are reached. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 295. | FNA vol. 7, p. 331. |
Parent taxa | Brassicaceae > tribe Arabideae > Draba | Brassicaceae > tribe Arabideae > Draba |
Sibling taxa | ||
Synonyms | D. aureola var. paniculata | D. nivalis var. brevicula, D. porsildii var. brevicula |
Name authority | S. Watson: in W. H. Brewer et al., Bot. California 2: 430. (1880) | G. A. Mulligan: Canad. J. Bot. 52: 1795, fig. 8. (1974) |
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