Draba standleyi |
Draba arida |
|
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Standley's Draba |
desert Draba |
|
Habit | Perennials; (densely pulvinate); caudex branched (with persistent, thickened petioles, branches compact); not scapose. | Perennials; (cespitose); caudex branched (with persistent leaf remains, branches relatively short); not scapose. |
Stems | unbranched, 0.3–1.3(–1.7) dm, usually glabrous throughout or sparsely pubescent proximally, rarely sparsely pubescent distally, trichomes simple and 2-rayed, 0.1–0.7 mm. |
usually unbranched, (0.3–)0.4–1 dm, pubescent throughout, trichomes simple and 2-rayed, 0.4–1.4 mm, and shorter, 2–4-rayed ones, 0.05–0.3 mm. |
Basal leaves | (not imbricate); rosulate; petiolate; petiole ciliate, (trichomes usually simple, rarely 2-rayed, not setiform); blade narrowly oblanceolate to linear-lanceolate, (strongly differentiated into blade and petiole), (1.2–)1.8–6(–8.5) cm × 1–5(–7) mm, margins entire or sparsely denticulate, (ciliate as petiole; midvein not prominent), surfaces glabrous or pubescent, usually with simple trichomes 0.1–0.8 mm, rarely 2-rayed. |
rosulate; subsessile; petiole not ciliate; blade obovate to spatulate or oblanceolate, 0.6–1.9(–2.4) cm × 2–5(–8) mm, (base ciliate, trichomes simple and 2-rayed), margins entire, surfaces abaxially pubescent with stalked, (2–)4-rayed trichomes, 0.3–0.6 mm, adaxially with simple and stalked, 2-rayed trichomes, 0.3–0.6 mm, and smaller, 3- or 4-rayed ones. |
Cauline leaves | 1–8; sessile; blade lanceolate to narrowly oblong, margins usually entire, surfaces pubescent as basal. |
(1 or) 2–5; sessile; blade oblong to oblanceolate or ovate, margins entire, surfaces pubescent as basal. |
Racemes | 5–17(–23)-flowered, ebracteate, elongated in fruit; rachis not flexuous, usually glabrous, rarely pubescent, trichomes simple and 2-rayed, (non-crisped). |
12–40-flowered, ebracteate, slightly elongated in fruit; rachis not flexuous, pubescent, trichomes simple and 2–4-rayed. |
Flowers | sepals ovate, 2–2.5 mm, pubescent, (trichomes simple); petals yellow, oblanceolate, 4–6 × 1.5–2 mm; anthers oblong, 0.6–0.8 mm. |
sepals broadly ovate, 2–2.7 mm, pubescent, (trichomes simple and short-stalked, 2–4-rayed); petals yellow, spatulate to oblanceolate, 3.5–5 × 1.4–2 mm; anthers oblong, 0.4–0.6 mm. |
Fruiting pedicels | divaricate-ascending or ascending, straight, 3–9(–13) mm, usually glabrous, rarely sparsely pubescent, trichomes simple. |
horizontal to divaricate-ascending, straight, (3–)4–8 mm, pubescent, trichomes simple and 2–4-rayed (0.1–0.5 mm). |
Fruits | linear-elliptic to elliptic, twisted or plane, flattened, 5–10(–13) × 1.5–2.5 mm; valves usually glabrous, rarely puberulent, trichomes simple, 0.05–0.1 mm; ovules 12–24 per ovary; style 0.7–1.4(–1.8) mm. |
elliptic or ovate to lanceolate, plane, slightly inflated basally, 4–7 × 2.5–3.5 mm; valves pubescent, trichomes simple and stalked, 2–4-rayed, 0.05–0.4 mm; ovules 8–12 per ovary; style 0.5–1.2(–1.4) mm. |
Seeds | ovoid, 1–1.2 × 0.7–0.8 mm. |
ovoid, 1–1.4 × 0.6–0.8 mm. |
2n | = 24. |
|
Draba standleyi |
Draba arida |
|
Phenology | Flowering Jun–Aug. | Flowering May–Jul. |
Habitat | Igneous rock outcrops, stabilized talus slopes | Rock crevices and gravelly soil in conifer and subalpine shrub communities |
Elevation | 1800-3100 m (5900-10200 ft) | 2100-3400 m (6900-11200 ft) |
Distribution |
AZ; NM; TX |
NV |
Discussion | Of conservation concern. Draba standleyi is a distinctive species that is sporadically distributed in the mountains of southwestern United States. It is known from the Chiricahua Mountains (Cochise County, southeastern Arizona), the Organ Mountains and Black Range (Dona Ana and Sierra counties, south-central New Mexico), and the Davis Mountains (Jeff Davis County, western Texas). It has not been reported from Mexico, though it is very likely to occur there. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Of conservation concern. Draba arida is a sexually reproducing, diploid member of the D. ventosa complex that may have been involved in the origin of the more widespread apomictic triploids (M. A. Beilstein and M. D. Windham 2003). The species is known from the Monitor, Toiyabe, and Toquima ranges in Lander and Nye counties. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 340. | FNA vol. 7, p. 292. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | D. gilgiana, D. chrysantha var. gilgiana | |
Name authority | J. F. Macbride & Payson: Ann. Missouri Bot. Gard. 5: 150. (1918) | C. L. Hitchcock: Revis. Drabas W. N. Amer., 52, plate 3, fig. 23. (1941) |
Web links |