Draba hitchcockii |
Draba yukonensis |
|
---|---|---|
lost river Draba |
Yukon whitlowgrass |
|
Habit | Perennials; (densely cespitose); caudex branched (densely covered 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, (0.1–)0.3–1(–1.3) dm, hirsute throughout, trichomes simple, 0.4–1 mm, and 2–4-rayed, 0.1–0.6 mm. |
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 | (densely imbricate); rosulate; sessile; blade narrowly oblanceolate to oblong-linear, 0.3–1.2(–1.5) cm × 1–2 mm, margins entire, (ciliate, trichomes simple, 0.3–1.2 mm), surfaces pubescent abaxially with stalked, 2–4-rayed trichomes, 0.08–0.45 mm, (midvein obscure), adaxially glabrous proximally, sparsely pubescent distally with mostly simple trichomes. |
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 | 4–15-flowered, ebracteate, elongated in fruit; rachis not flexuous, hirsute as stem. |
5–20-flowered, ebracteate, considerably elongated in fruit; rachis not flexuous, pubescent as stem. |
Flowers | sepals oblong, 2.5–3.5 mm, hirsute, (trichomes simple and stalked, 2–4-rayed); petals white, obovate, 5–6.5 × 2–3.5 mm; anthers ovate, 0.5–0.6 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 | ascending, straight, (2–)4–13(–18) mm, hirsute as stem. |
erect to ascending, straight, 0.5–3 mm, pubescent as stem. |
Fruits | ovate to broadly oblong or elliptic, plane, flattened, (3–)4–7(–10) × (2.5–)3.5–5 mm; valves pubescent, trichomes simple and short-stalked, 2(–4)-rayed, 0.06–0.5 mm; ovules 8–12 per ovary; style (0.8–)1–1.7(–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, 1.4–1.8 × 0.8–1 mm. |
oblong, 0.6–0.8 × 0.3–0.4 mm. |
2n | = 54. |
|
Draba hitchcockii |
Draba yukonensis |
|
Phenology | Flowering May–Jun. | Flowering late May–Jun. |
Habitat | Limestone outcrops and gravelly soil | Open stony ridges on ancient beach in grassy areas and aspen stands |
Elevation | 1800-2200 m (5900-7200 ft) | ca. 600 m (ca. 2000 ft) |
Distribution |
ID |
YT |
Discussion | Draba hitchcockii is known from the Lost River Range in Butte and Custer counties. Based on morphological and chromosomal evidence, M. D. Windham (2004) suggested that it may be an allopolyploid resulting from hybridization between D. oreibata and D. paysonii. Draba hitchcockii is superficially similar to D. jaegeri, a taxon known from the Charleston Mountains of Clark County, Nevada. Both are cespitose perennials with relatively large, white flowers and a chromosome number (2n = 54) otherwise unknown in Draba (Windham). Features distinguishing these two taxa are provided in the discussion of 51. D. jaegeri. (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. 311. | FNA vol. 7, p. 346. |
Parent taxa | ||
Sibling taxa | ||
Name authority | Rollins: J. Arnold Arbor. 64: 500. (1983) | A. E. Porsild: Publ. Bot. (Ottawa) 4: 37, plate 7. (1975) |
Web links |