Draba oreibata |
Draba yukonensis |
|
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limestone Draba |
Yukon whitlowgrass |
|
Habit | Perennials; (cespitose); caudex branched (with persistent leaves, branches sometimes terminating in sterile rosettes); scapose. | Perennials; (short-lived); caudex simple or branched (with persistent leaf remains); not scapose. |
Stems | unbranched, 0.2–0.9 dm, glabrous throughout. |
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 | rosulate; sessile; blade oblong to narrowly oblanceolate, 0.2–1 cm × 0.6–2(–4) mm, margins entire, (ciliate, trichomes simple, 0.1–0.5 mm, apex obtuse), surfaces glabrous. |
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. |
1–3; sessile; blade ovate to oblong, margins entire, surfaces pubescent as basal. |
Racemes | 3–8-flowered, ebracteate, considerably elongated in fruit; rachis slightly flexuous, glabrous. |
5–20-flowered, ebracteate, considerably elongated in fruit; rachis not flexuous, pubescent as stem. |
Flowers | sepals oblong, 1.7–2.5 mm, glabrous; petals white, oblanceolate to obovate, 3.5–4.5 × 1.2–2 mm; anthers ovate, 0.3–0.4 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 to ascending, straight, 4–13 mm, glabrous. |
erect to ascending, straight, 0.5–3 mm, pubescent as stem. |
Fruits | oblong to narrowly so, slightly twisted, flattened, 5–9 × 1.5–3 mm; valves glabrous; ovules 8–16 per ovary; style 0.3–0.9(–1.2) 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, 0.9–1.3 × 0.6–0.8 mm. |
oblong, 0.6–0.8 × 0.3–0.4 mm. |
2n | = 32. |
|
Draba oreibata |
Draba yukonensis |
|
Phenology | Flowering May–Jul. | Flowering late May–Jun. |
Habitat | Limestone cliffs, talus | Open stony ridges on ancient beach in grassy areas and aspen stands |
Elevation | 1800-2700 m (5900-8900 ft) | ca. 600 m (ca. 2000 ft) |
Distribution |
ID |
YT |
Discussion | R. C. Rollins (1993) and N. H. Holmgren (2005b) divided Draba oreibata into two varieties: the Idaho endemic var. oreibata and the Nevada endemic var. serpentina. 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, and distinguished by characteristics discussed by Al-Shehbaz and Windham. Draba oreibata, in the strict sense, is known from Blaine, Butte, Clark, Custer, and Lemhi counties. (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. 325. | FNA vol. 7, p. 346. |
Parent taxa | ||
Sibling taxa | ||
Name authority | J. F. Macbride & Payson: Amer. J. Bot. 4: 257. (1917) | A. E. Porsild: Publ. Bot. (Ottawa) 4: 37, plate 7. (1975) |
Web links |