Draba cinerea |
Draba pennellii |
|
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gray-leaf Draba, gray-leaf whitlow-grass |
schell creek Draba |
|
Habit | Perennials; (cespitose); caudex simple or branched; rarely scapose. | Perennials; (cespitose, often forming mats); caudex branched (elongated, with persistent leaf bases, branches sometimes terminating in sterile rosettes); sometimes scapose. |
Stems | unbranched, (0.3–)0.5–1.6(–2.7) dm, pubescent throughout, trichomes 4–10-rayed, 0.1–0.3 mm, (often some rays branched, simple trichomes sparse, to 0.6 mm). |
unbranched, (0.15–)0.3–0.7(–1) dm, pubescent proximally, trichomes simple and spurred, 0.4–0.8 mm, and short-stalked, 2–4-rayed, 0.1–0.4 mm, (sometimes with simple trichomes distally). |
Basal leaves | rosulate; petiolate; petiole base and proximalmost margin ciliate, (trichomes simple, 0.2–0.8 mm); blade oblanceolate to narrowly obovate or linear-lanceolate, 0.4–1.5 cm × 1–5 mm, margins usually entire, rarely with 1 tooth on each side, surfaces densely pubescent with minutely stalked, stellate, 8–12-rayed, trichomes 0.1–0.25 mm, (midvein obscure abaxially, apex trichomes simple). |
subrosulate; sessile; blade oblanceolate to oblong, (0.3–)0.5–0.8 cm × 1–3 mm, (base ciliate, trichomes simple, 0.2–0.8 mm), margins entire, (not ciliate), surfaces usually pubescent, with stalked, (2–)4 (or 5)-rayed trichomes, 0.2–0.5 mm, adaxially sometimes glabrate, or primarily with simple trichomes, 0.3–0.8 mm. |
Cauline leaves | 0–3(–5); sessile; blade ovate or oblong to lanceolate, margins entire, surfaces pubescent as basal. |
(0 or) 1–4; sessile; blade ovate to oblong, margins entire, surfaces pubescent as basal. |
Racemes | (3–)5–17(–24)-flowered, ebracteate, elongated in fruit; rachis not flexuous, pubescent as stem. |
(3–)7–15(–20)-flowered, ebracteate, elongated in fruit; rachis not flexuous, pubescent as stem. |
Flowers | sepals ovate, 1.7–2.5 mm, pubescent, (trichomes simple and short-stalked, 2- or 3-rayed); petals white, spatulate to obovate, 3.5–4.5 × 1.5–2 mm; anthers ovate, 0.3–0.4 mm. |
sepals ovate to oblong, 2–3 mm, pubescent, (trichomes simple, with fewer, short-stalked, 2-rayed ones); petals white, obovate, 3.5–6 × 1.5–2.8 mm; anthers oblong, 0.5–0.6 mm. |
Fruiting pedicels | divaricate-ascending or ascending, straight, (3–)4–7(–9) mm, pubescent as stem. |
divaricate-ascending to ascending, straight, 3–10 mm, pubescent, trichomes simple and short-stalked, 2–4-rayed, (0.1–0.4 mm). |
Fruits | oblong to elliptic, plane, slightly flattened, 5–8 × 2–3 mm; valves pubescent, trichomes short-stalked, 2–5-rayed, 0.05–0.3 mm, (some rays branched); ovules 20–36(–42) per ovary; style (0.1–)0.2–1 mm. |
broadly or, rarely, narrowly lanceolate to elliptic or ovate, plane or slightly twisted, flattened, (4)5–8(–10) × 2–3.2 mm; valves (each with distinct midvein), pubescent, trichomes simple and short-stalked, 2-rayed, 0.08–0.2 mm; ovules 12–24 per ovary; style (0.7–)1–1.8(–2.1) mm. |
Seeds | ovoid, 0.6–0.8 × 0.4–0.6 mm. |
oblong, 0.9–1.3 × 0.7–1 mm. |
2n | = 48. |
= 32. |
Draba cinerea |
Draba pennellii |
|
Phenology | Flowering Jun–Jul. | Flowering May–Jul. |
Habitat | Rock outcrops, ridges, meadows, gravel beaches, stream banks, alluvial fans | Rock outcrops and talus slopes in pinyon-juniper, sagebrush, mountain shrub, and mixed conifer communities |
Elevation | 0-500 m (0-1600 ft) | 1900-3500 m (6200-11500 ft) |
Distribution |
AK; BC; NT; NU; ON; QC; SK; YT; Greenland; Europe (Finland, Norway, n Russia); e Asia (Russian Far East, Siberia) |
NV |
Discussion | Draba cinerea is a polymorphic species in which tetraploid, hexaploid, heptaploid, and octoploid chromosome counts (all based on x = 8) have been reported (e.g., R. C. Rollins 1993). Although we have not seen the type collection, we tentatively consider the taxon to be hexaploid, which is the predominant ploidy level throughout the species range, including North America, and also from its type region in Siberia. Hexaploid Draba cinerea is closely related to decaploid (2n = 80) D. arctica, from which it is distinguished with difficulty. In general, D. cinerea has 1–3(–5)-leaved stems, basal leaf blades usually not terminated with simple trichomes and with obscure midveins abaxially, petals 3.5–4.5 mm, and seeds 0.6–0.8 × 0.4–0.6 mm. By contrast, D. arctica has leafless or 1(–3)-leaved stems, basal leaf blades terminated with simple or 2-rayed trichomes and with midveins distinct abaxially, petals 3.5–6 mm, and seeds (0.8–)0.9–1.1 × (0.6–)0.7–0.8 mm. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Of conservation concern. Draba pennellii is known from White Pine County in east-central Nevada. It is easily distinguished from other white-flowered species in the region by its elongated, many-branched caudices, long styles, usually few-leaved or, rarely, leafless flowering stems, and distinct midvein on fruit valves. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 300. | FNA vol. 7, p. 329. |
Parent taxa | Brassicaceae > tribe Arabideae > Draba | Brassicaceae > tribe Arabideae > Draba |
Sibling taxa | ||
Synonyms | D. magellanica subsp. cinerea | |
Name authority | Adams: Mém Soc. Imp. Naturalistes Moscou 5: 103. (1817) | Rollins: J. Arnold Arbor. 64: 502. (1983) |
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