Draba incerta |
Draba paysonii |
|
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whitlow-wort, Yellowstone Draba, Yellowstone Draba whitlow-wort, Yellowstone whitlow-grass, Yellowstone whitlow-wort |
Payson's 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, densely pulvinate); caudex branched (covered with persistent leaves, branches creeping, 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, 0.05–0.3 dm, densely pubescent throughout, trichomes simple, 0.4–1.3 mm, and stalked, 2–5-rayed, stellate, 0.1–0.6 mm. |
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. |
(imbricate); rosulate; sessile; blade linear to linear-oblanceolate, 0.4–1.2 cm × 0.8–1.5 mm, margins entire, (ciliate, trichomes simple and spurred, (0.4–)0.6–1.4 mm), surfaces pubescent, abaxially (dense) with stalked, 2–12-rayed trichomes, 0.1–0.8 mm, adaxially with simple and 2-rayed ones, 0.3–1 mm, (midvein prominent). |
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. |
2–7-flowered, ebracteate, slightly elongated in fruit; rachis not flexuous, pubescent as stem. |
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, 2.8–3.5 mm, pubescent, (trichomes simple and short-stalked, 2–4-rayed); petals pale yellow, oblanceolate to spatulate, (4–)5–6 × (1.5–)2–3 mm; anthers oblong, 0.5–0.7 mm. |
Fruiting pedicels | ascending, straight, (2.5–)4–11(–27) mm, glabrous or pubescent, trichomes 2–5-rayed or pectinate. |
divaricate-ascending, straight, 3–9 mm, pubescent, trichomes simple (0.4–1.4 mm), and stalked, 2–5-rayed (0.1–0.6 mm). |
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. |
often broadly ovoid to lanceolate, plane, slightly inflated basally, (5–)6–9 × (3–)3.7–5 mm; valves densely pubescent, trichomes simple and 2-rayed, (0.2–)0.4–1 mm, (occasionally with fewer, smaller, 4- or 5-rayed ones); ovules 8–12 per ovary; style (0.6–)0.8–1.2 mm. |
Seeds | oblong, 1.1–1.5 × 0.7–1 mm. |
oblong, 1.7–2.2 × 1–1.4 mm. |
2n | = 112. |
|
Draba incerta |
Draba paysonii |
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Phenology | Flowering Jun–Aug. | Flowering Jun–Jul. |
Habitat | Rock outcrops, talus, gravelly areas, tundra | Limestone rock outcrops, talus, gravelly calcareous soil |
Elevation | 0-3300 m (0-10800 ft) | 1800-3500 m (5900-11500 ft) |
Distribution |
AK; CO; ID; MT; NV; UT; WA; WY; AB; BC; QC; YT
|
MT; WY |
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.) |
Draba paysonii is known from southwestern Montana (Gallatin, Glacier, Madison, and Meagher counties) and northwestern Wyoming (Fremont and Park counties). Reports of its occurrence in Alberta (e.g., G. A. Mulligan 1971b) are based on plants of D. novolympica, a species formerly treated as D. paysonii var. treleasei. Features distinguishing these two species are discussed under 70. D. novolympica. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 313. | FNA vol. 7, p. 327. |
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. vestita |
Name authority | Payson: Amer. J. Bot. 4: 261. (1917) | J. F. Macbride: Contr. Gray Herb. 56: 52. (1918) |
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