Draba aureola |
Draba ramulosa |
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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 |
Tushar Mountain Draba |
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Habit | Perennials; (short-lived); caudex simple or branched (poorly developed, with persistent dry leaves); not scapose. | Perennials; (loosely matted, grayish); caudex branched (with persistent leaf bases, branches creeping, sometimes terminating in sterile rosettes); not 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, 0.4–0.6 dm, densely pubescent throughout, trichomes dendritic, 3–6-rayed, (often crisped), 0.1–0.4 mm. |
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. |
(imbricate); not rosulate; sessile; blade obovate to oblanceolate, 0.4–1.1 cm × 2–3.2 mm, margins entire, (base and margins not ciliate), surfaces pubescent with stalked, 4–8-rayed trichomes, 0.1–0.5 mm, (sometimes 1 or more rays spurred), adaxially sometimes trichomes simple. |
Cauline leaves | 5–33; sessile; blade oblong to linear, margins entire, surfaces pubescent as basal. |
2 or 3 (sometimes basal leaves spaced, flowering stem appearing to 8-leaved); sessile; blade oblong to ovate, 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. |
4–15-flowered, ebracteate or proximalmost 1 or 2 flowers bracteate, slightly elongated in fruit; rachis not flexuous, pubescent as stem. |
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 broadly ovate, 1.7–2.4 mm, pubescent, (trichomes short-stalked, 2–5-rayed); petals yellow, obovate to oblanceolate, 3–4.5 × 1.5–2.5 mm; anthers ovate, 0.4–0.5 mm. |
Fruiting pedicels | horizontal to divaricate, usually straight, rarely curved upward, (3–)5–12(–19) mm, hirsute as stem. |
divaricate-ascending, usually straight, rarely curved upward, 3–6(–10) mm, pubescent, trichomes 3–6-rayed, (crisped, 0.1–0.4 mm), and, sometimes, simple. |
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. |
(not appressed to rachis), ovate to elliptic, plane, flattened, 4–6.5 × 2.5–4 mm; valves densely pubescent, trichomes simple and short-stalked, 2–5-rayed, 0.08–0.35 mm; ovules 6–12 per ovary; style (0.1–)0.3–0.7 mm. |
Seeds | oblong, 1.4–1.9 × 0.8–1.1 mm. |
oblong, 1.4–1.8 × 0.8–1.2 mm. |
2n | = 20. |
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Draba aureola |
Draba ramulosa |
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Phenology | Flowering Jul–Aug. | Flowering Jun–Aug. |
Habitat | Open conifer forests, alpine meadows and moraines, talus slopes | Rock outcrops, talus, gravelly soils |
Elevation | 2200-3200 m (7200-10500 ft) | 3300-3600 m (10800-11800 ft) |
Distribution |
CA; OR; WA
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UT |
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.) |
Of conservation concern. Molecular and chromosomal data (M. D. Windham, unpubl.) strongly suggest that Draba ramulosa is an allopolyploid species. It is thought to have originated through hybridization between D. sobolifera and a member of the white-flowered, euploid lineage of M. A. Beilstein and M. D. Windham (2003). It is easily distinguished from D. sobolifera by having pale yellow to whitish (versus bright yellow) petals, grayish (versus green) foliage, non-ciliate (versus ciliate) basal leaves pubescent with 4–8-rayed (versus 2–4-rayed) trichomes, often proximally bracteate (versus ebracteate) racemes, and flattened (versus inflated basally) fruits. Draba ramulosa is known from the Tushar Mountains in south-central Utah (Beaver and Piute counties). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 295. | FNA vol. 7, p. 332. |
Parent taxa | Brassicaceae > tribe Arabideae > Draba | Brassicaceae > tribe Arabideae > Draba |
Sibling taxa | ||
Synonyms | D. aureola var. paniculata | |
Name authority | S. Watson: in W. H. Brewer et al., Bot. California 2: 430. (1880) | Rollins: Contr. Gray Herb. 214: 6. (1984) |
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