Draba incerta |
Draba oreibata |
|
---|---|---|
whitlow-wort, Yellowstone Draba, Yellowstone Draba whitlow-wort, Yellowstone whitlow-grass, Yellowstone whitlow-wort |
limestone Draba |
|
Habit | Perennials; (cespitose, often pulvinate); caudex branched (dense with persistent leaf remains, branches sometimes terminating in sterile rosettes); scapose. | Perennials; (cespitose); caudex branched (with persistent leaves, branches sometimes terminating in sterile rosettes); scapose. |
Stems | unbranched, (0.2–)0.4–1.4(–2.1) dm, often pubescent throughout, sometimes glabrous distally, trichomes often simple and 2–5-rayed, 0.1–0.5 mm, (sometimes with mostly subpectinate ones). |
unbranched, 0.2–0.9 dm, glabrous throughout. |
Basal leaves | rosulate; petiolate; petiole (0–1 cm), ciliate throughout; blade narrowly oblanceolate to linear, (0.4–)0.6–1.7(–2.5) cm × (1–)1.5–3.5(–5) mm, margins entire, (ciliate, trichomes usually simple, rarely 2-rayed, 0.2–1.1 mm), surfaces usually pubescent with short-stalked, pectinate trichomes, 0.15–0.5 mm, sometimes also with 4–6-rayed ones, (midvein usually obscure abaxially), sometimes glabrous adaxially. |
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 | usually 0 (or 1, as a bract); sessile; blade linear to oblong, margins entire, surfaces pubescent as basal. |
0. |
Racemes | 3–14(–30)-flowered, usually ebracteate, rarely proximalmost flowers bracteate, elongated in fruit; rachis not flexuous, glabrous or pubescent as stem. |
3–8-flowered, ebracteate, considerably elongated in fruit; rachis slightly flexuous, glabrous. |
Flowers | sepals broadly ovate, 2.5–3.5(–4) mm, pubescent, (trichomes simple and 2- or 3-rayed); petals yellow (fading white), oblanceolate to obovate, 4–6 × 1.5–2.5 mm; anthers ovate, 0.3–0.5 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, (2.5–)4–11(–27) mm, glabrous or pubescent, trichomes 2–5-rayed or pectinate. |
divaricate-ascending to ascending, straight, 4–13 mm, glabrous. |
Fruits | broadly ovate to lanceolate, plane, flattened, 5–9(–11) × 2–4 mm; valves glabrous or puberulent, trichomes simple and 2-rayed, 0.05–0.3 mm; ovules 8–16(–20) per ovary; style 0.2–0.9 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, 1.1–1.5 × 0.7–1 mm. |
oblong, 0.9–1.3 × 0.6–0.8 mm. |
2n | = 112. |
= 32. |
Draba incerta |
Draba oreibata |
|
Phenology | Flowering Jun–Aug. | Flowering May–Jul. |
Habitat | Rock outcrops, talus, gravelly areas, tundra | Limestone cliffs, talus |
Elevation | 0-3300 m (0-10800 ft) | 1800-2700 m (5900-8900 ft) |
Distribution |
AK; CO; ID; MT; NV; UT; WA; WY; AB; BC; QC; YT
|
ID |
Discussion | Draba incerta was shown by G. A. Mulligan (1972) to be sexually reproducing and 14-ploid with x = 8. It is often confused with the apomict D. oligosperma (2n = 32, 64). Draba incerta is readily separated from D. oligosperma by having well-formed (versus abortive) anthers and pollen, stalked (versus sessile) leaf trichomes, and ciliate (versus non-ciliate) basal leaves with obscure (versus prominent) midveins. Although both species have leafless scapes, one often finds a bract adnate to, or subtending, the proximalmost pedicel in D. incerta. Draba incerta is found near sea level in Alaska. (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. 313. | FNA vol. 7, p. 325. |
Parent taxa | Brassicaceae > tribe Arabideae > Draba | Brassicaceae > tribe Arabideae > Draba |
Sibling taxa | ||
Synonyms | D. exalata, D. incerta var. laevicapsula, D. incerta var. peasei, D. laevicapsula, D. peasei | |
Name authority | Payson: Amer. J. Bot. 4: 261. (1917) | J. F. Macbride & Payson: Amer. J. Bot. 4: 257. (1917) |
Web links |
|