Draba incerta |
Draba malpighiacea |
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whitlow-wort, Yellowstone Draba, Yellowstone Draba whitlow-wort, Yellowstone whitlow-grass, Yellowstone whitlow-wort |
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Habit | Perennials; (cespitose, often pulvinate); caudex branched (dense with persistent leaf remains, branches sometimes terminating in sterile rosettes); scapose. | Perennials; caudex simple or branched (sometimes with persistent leaf bases); not 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, 0.5–1.5 dm, pubescent throughout, trichomes malpighiaceous, 0.2–0.5 mm, and sometimes simple. |
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 not ciliate; blade oblanceolate to spatulate, 0.5–1.8 cm × 2–4 mm, margins entire or dentate, (not ciliate proximally), surfaces pubescent with malpighiaceous trichomes, 0.3–0.6 mm. |
Cauline leaves | usually 0 (or 1, as a bract); sessile; blade linear to oblong, margins entire, surfaces pubescent as basal. |
4–13; sessile; blade broadly ovate to lanceolate, margins denticulate, 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. |
10–33-flowered, ebracteate, elongated in fruit; rachis not flexuous, glabrous or pubescent, trichomes simple and/or malpighiaceous. |
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, 2.5–3 mm, subapically pubescent, (trichomes simple and malpighiaceous); petals yellow, oblanceolate, 4–5 × 1.5–2 mm; anthers oblong, 0.7–1 mm. |
Fruiting pedicels | ascending, straight, (2.5–)4–11(–27) mm, glabrous or pubescent, trichomes 2–5-rayed or pectinate. |
divaricate-ascending, straight or curved upward, 6–13 mm, pubescent abaxially, trichomes simple and/or malpighiaceous. |
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 elliptic-lanceolate, plane, flattened, 5–10 × 1.5–2.2 mm; valves glabrous; ovules 14–18 per ovary; style 0.8–1.2 mm. |
Seeds | oblong, 1.1–1.5 × 0.7–1 mm. |
ovoid, 1–1.4 × 0.7–0.9 mm. |
2n | = 112. |
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Draba incerta |
Draba malpighiacea |
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Phenology | Flowering Jun–Aug. | Flowering Jun–Aug. |
Habitat | Rock outcrops, talus, gravelly areas, tundra | Rock outcrops and rocky slopes in subalpine conifer forests |
Elevation | 0-3300 m (0-10800 ft) | 3000-3500 m (9800-11500 ft) |
Distribution |
AK; CO; ID; MT; NV; UT; WA; WY; AB; BC; QC; YT
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CO |
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 malpighiacea, which is restricted to higher elevations in Hinsdale, La Plata, and Montezuma counties, has been included within D. spectabilis by previous authors. Preliminary data suggest that it is one of the diploid parents of tetraploid D. spectabilis. It is readily distinguished from all species of Draba in Canada and the United States by having a leaf indumentum of exclusively malpighiaceous trichomes. The only other species in the flora area with such trichomes is D. sibirica, a stoloniferous, scapose perennial known only from Greenland. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 313. | FNA vol. 7, p. 318. |
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) | Windham & Al-Shehbaz: Harvard Pap. Bot. 12: 417. (2007) |
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