Draba incerta |
Draba pterosperma |
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whitlow-wort, Yellowstone Draba, Yellowstone Draba whitlow-wort, Yellowstone whitlow-grass, Yellowstone whitlow-wort |
wing-seed Draba, wingedseed Draba |
|
Habit | Perennials; (cespitose, often pulvinate); caudex branched (dense with persistent leaf remains, branches sometimes terminating in sterile rosettes); scapose. | Perennials; (densely cespitose to pulvinate); 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, 0.3–1.1 dm, pubescent throughout, trichomes sub-dendritic, 2–7-rayed, (often crisped), 0.2–0.7 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. |
(densely imbricate); rosulate; petiolate; petiole base and margin ciliate, (trichomes simple or branched, often crisped, 0.3–1 mm); blade oblanceolate to obovate or spatulate, 0.2–0.7 cm × 1–2.8 mm, margins entire, surfaces densely pubescent (often grayish) with stellate-dendritic, stalked, 5–12-rayed, (often crisped) trichomes, 0.2–0.6 mm. |
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. |
4–12-flowered, ebracteate, 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, 3–4 mm, pubescent, (trichomes stalked, branched, crisped); petals yellow, oblanceolate, 6–7 × 1.5–2.5 mm; anthers oblong, 0.7–0.9 mm. |
Fruiting pedicels | ascending, straight, (2.5–)4–11(–27) mm, glabrous or pubescent, trichomes 2–5-rayed or pectinate. |
erect (and subappressed to rachis) or ascending, straight, (3–)4–9(–12) mm, pubescent as stem. |
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. |
broadly ovate to lanceolate or subelliptic, plane, flattened, 5–10(–13) × (2.5–)3.5–5(–6) mm; valves pubescent, trichomes short stalked, 2–7-rayed, (straight or crisped), 0.15–0.6 mm; ovules 8–12 per ovary; style 1.5–3(–3.8) mm. |
Seeds | oblong, 1.1–1.5 × 0.7–1 mm. |
(winged), ovate, 1.6–3 × 1.3–1.8 mm; (wing 0.3–0.9 mm wide). |
2n | = 112. |
|
Draba incerta |
Draba pterosperma |
|
Phenology | Flowering Jun–Aug. | Flowering Jun–Sep. |
Habitat | Rock outcrops, talus, gravelly areas, tundra | Limestone and marble outcrops, talus, gravel slopes |
Elevation | 0-3300 m (0-10800 ft) | 1500-2500 m (4900-8200 ft) |
Distribution |
AK; CO; ID; MT; NV; UT; WA; WY; AB; BC; QC; YT
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CA |
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 pterosperma is a distinctive species that is restricted to the Marble Mountains of northern California (Siskiyou County). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 313. | FNA vol. 7, p. 332. |
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) | Payson: Amer. J. Bot. 4: 266. (1917) |
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