Draba incerta |
Draba oblongata |
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whitlow-wort, Yellowstone Draba, Yellowstone Draba whitlow-wort, Yellowstone whitlow-grass, Yellowstone whitlow-wort |
Canadian arctic Draba |
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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 leaf remains); sometimes 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–)0.4–1.5(–1.9) dm, pubescent throughout, trichomes simple, 0.4–0.8 mm, and short-stalked, 4–10-rayed, 0.05–0.3 mm, (mostly branched distally). |
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; petiolate; petiole base and margin ciliate, (trichomes simple, 0.3–1 mm); blade oblanceolate to lanceolate, 0.4–1.5 cm × 1.5–5 mm, margins entire, surfaces pubescent with simple and stalked, 2- or 3-rayed trichomes, 0.4–1 mm, with short-stalked, 8–12-rayed, stellate ones, 0.1–0.2 mm. |
Cauline leaves | usually 0 (or 1, as a bract); sessile; blade linear to oblong, margins entire, surfaces pubescent as basal. |
0–2; sessile; blade oblong to broadly ovate, margins entire, surfaces pubescent as basal. |
Racemes | 3–14(–30)-flowered, usually ebracteate, rarely proximalmost flowers bracteate, elongated in fruit; rachis not flexuous, glabrous or pubescent as stem. |
5–13(–18)-flowered, ebracteate, elongated in fruit; rachis not flexuous, pubescent as stem distally. |
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 ovate, 2–3 mm, pubescent, (trichomes simple and short-stalked, mostly 2-rayed); petals white, spatulate to obovate, 3.5–5 × 1.5–2.5 mm; anthers ovate, 0.2–0.3 mm. |
Fruiting pedicels | ascending, straight, (2.5–)4–11(–27) mm, glabrous or pubescent, trichomes 2–5-rayed or pectinate. |
divaricate to ascending, straight, 2–6(–8) mm, pubescent as rachis. |
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. |
elliptic to oblong, plane, slightly flattened, 4–8(–9.5) × 2–3(–4) mm; valves pubescent, trichomes short-stalked, (2–)5–12-rayed, 0.05–3 mm; ovules 24–36 per ovary; style 0.2–0.8 mm (stigma considerably wider than style, often appearing 2-lobed). |
Seeds | oblong, 1.1–1.5 × 0.7–1 mm. |
ovate, 0.7–1 × 0.5–0.6 mm. |
2n | = 112. |
= 64. |
Draba incerta |
Draba oblongata |
|
Phenology | Flowering Jun–Aug. | Flowering Jun–Jul. |
Habitat | Rock outcrops, talus, gravelly areas, tundra | Ridges and hillsides, sand and gravel flood plains, swales, tundra |
Elevation | 0-3300 m (0-10800 ft) | 0-400 m (0-1300 ft) |
Distribution |
AK; CO; ID; MT; NV; UT; WA; WY; AB; BC; QC; YT
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AK; NT; NU; Greenland; e Asia (Russian Far East, Siberia) |
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.) |
Plants of Draba oblongata are occasionally misidentified as decaploid (2n = 80) D. arctica, but the former is readily separated by a preponderance of simple (versus stellate) trichomes on both leaf blade surfaces. Draba oblongata is sometimes confused with D. micropetala, but the latter has pale yellow (versus white) flowers, fruits pubescent with simple and spurred (versus (2–)5–12-rayed) trichomes, and stigmas as wide as (versus much wider than) the style. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 313. | FNA vol. 7, p. 323. |
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 | D. arctica subsp. groenlandica, D. cinerea subsp. groenlandica, D. groenlandica |
Name authority | Payson: Amer. J. Bot. 4: 261. (1917) | R. Brown ex de Candolle: Syst. Nat. 2: 342. (1821) |
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