Draba hitchcockii |
Draba oreibata |
|
---|---|---|
lost river Draba |
limestone Draba |
|
Habit | Perennials; (densely cespitose); caudex branched (densely covered with persistent leaves, branches sometimes terminating in sterile rosettes); scapose. | Perennials; (cespitose); caudex branched (with persistent leaves, branches sometimes terminating in sterile rosettes); 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. |
unbranched, 0.2–0.9 dm, glabrous throughout. |
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; 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. |
Cauline leaves | 0. |
0. |
Racemes | 4–15-flowered, ebracteate, elongated in fruit; rachis not flexuous, hirsute as stem. |
3–8-flowered, ebracteate, considerably elongated in fruit; rachis slightly flexuous, glabrous. |
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 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. |
Fruiting pedicels | ascending, straight, (2–)4–13(–18) mm, hirsute as stem. |
divaricate-ascending to ascending, straight, 4–13 mm, glabrous. |
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. |
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. |
Seeds | oblong, 1.4–1.8 × 0.8–1 mm. |
oblong, 0.9–1.3 × 0.6–0.8 mm. |
2n | = 54. |
= 32. |
Draba hitchcockii |
Draba oreibata |
|
Phenology | Flowering May–Jun. | Flowering May–Jul. |
Habitat | Limestone outcrops and gravelly soil | Limestone cliffs, talus |
Elevation | 1800-2200 m (5900-7200 ft) | 1800-2700 m (5900-8900 ft) |
Distribution |
ID |
ID |
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.) |
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.) |
Source | FNA vol. 7, p. 311. | FNA vol. 7, p. 325. |
Parent taxa | ||
Sibling taxa | ||
Name authority | Rollins: J. Arnold Arbor. 64: 500. (1983) | J. F. Macbride & Payson: Amer. J. Bot. 4: 257. (1917) |
Web links |