Draba oreibata |
Draba petrophila |
|
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limestone Draba |
Santa Rita Mountain Draba, Santa Rita Mountain whitlowgrass, Santa Rita whitlow grass |
|
Habit | Perennials; (cespitose); caudex branched (with persistent leaves, branches sometimes terminating in sterile rosettes); scapose. | Perennials; (cespitose, long-lived); caudex simple or branched (covered with persistent petioles), not scapose. |
Stems | unbranched, 0.2–0.9 dm, glabrous throughout. |
usually unbranched, rarely branched, 0.3–1.9(–2.8) dm, moderately to densely hirsute throughout, trichomes simple, 0.2–1.3 mm, with short-stalked to subsessile, cruciform, 0.02–0.4 mm, and 2-rayed ones, 0.3–0.9 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; petiolate; petiole ciliate, (trichomes simple, 0.4–1.5 mm); blade oblanceolate, 1–5(–6) cm × 2–5(–10) mm, margins usually entire, rarely denticulate, surfaces pubescent, abaxially with stalked, cruciform trichomes, 0.07–0.5 mm, adaxially often similar, sometimes with fewer, simple and 2-rayed trichomes, 0.4–1.3 mm. |
Cauline leaves | 0. |
3–10; sessile; blade ovate to lanceolate or oblong, margins entire or denticulate, surfaces pubescent as basal. |
Racemes | 3–8-flowered, ebracteate, considerably elongated in fruit; rachis slightly flexuous, glabrous. |
10–37(–58)-flowered, ebracteate, 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 oblong, 2–3.5 mm, pubescent, (trichomes simple and 2-rayed); petals yellow, oblanceolate, 3.5–6 × 1.2–1.8 mm; anthers oblong, 0.8–1 mm. |
Fruiting pedicels | divaricate-ascending to ascending, straight, 4–13 mm, glabrous. |
divaricate-ascending, straight, 4–10 mm, pubescent throughout, trichomes simple (0.1–0.5 mm) and subsessile, 2–4-rayed, (0.03–0.2 mm). |
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. |
lanceolate to elliptic, often strongly twisted, flattened, 5–11 × 2–3 mm; valves puberulent at least along margin, trichomes simple, antrorse, 0.03–0.15 mm; ovules 14–24 per ovary; style 0.8–1.8(–2.5) mm. |
Seeds | oblong, 0.9–1.3 × 0.6–0.8 mm. |
ovoid, 1–1.4 × 0.6–0.9 mm. |
2n | = 32. |
|
Draba oreibata |
Draba petrophila |
|
Phenology | Flowering May–Jul. | Flowering Jul–Sep. |
Habitat | Limestone cliffs, talus | Crevices, ledges of cliffs |
Elevation | 1800-2700 m (5900-8900 ft) | 1200-2800 m (3900-9200 ft) |
Distribution |
ID |
AZ
|
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.) |
Draba petrophila is often broadly circumscribed to include the taxon herein called D. viridis. For a discussion of the differences between these species and the closely related D. helleriana, see I. A. Al-Shehbaz and M. D. Windham (2007). Draba petrophila, in the strict sense, is known only from Cochise, Pima, and Santa Cruz counties in southeastern Arizona. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 325. | FNA vol. 7, p. 329. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | D. helleriana var. blumeri, D. helleriana var. petrophila | |
Name authority | J. F. Macbride & Payson: Amer. J. Bot. 4: 257. (1917) | Greene: Pittonia 4: 17. (1899) |
Web links |