Draba incerta |
Draba ramosissima |
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whitlow-wort, Yellowstone Draba, Yellowstone Draba whitlow-wort, Yellowstone whitlow-grass, Yellowstone whitlow-wort |
branch 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; caudex branched (well-developed, 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 proximally, paniculately branched distally, 0.7–3.8(–5) dm, pubescent proximally, trichomes short-stalked, 2–4-rayed, 0.1–0.6 mm, sometimes with simple ones, 0.4–0.8 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. |
rosulate; petiolate; petiole (to 2 cm), ciliate (trichomes simple, 0.3–0.5 mm); blade oblanceolate, (0.7–)1–5.5 cm × 2–8 mm, margins dentate, surfaces pubescent with short-stalked to subsessile, 3- or 4-rayed trichomes, 0.1–0.5 mm, adaxially sometimes also simple, 0.4–1.3 mm. |
Cauline leaves | usually 0 (or 1, as a bract); sessile; blade linear to oblong, margins entire, surfaces pubescent as basal. |
(5–)7–15(–21); sessile; blade ovate to oblong or elliptic to lanceolate, margins usually coarsely dentate or serrate, rarely subpinnatifid, 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. |
9–28-flowered, ebracteate, paniculate; 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, 2.5–3 mm, pubescent, (trichomes simple and subsessile, 2–4-rayed); petals white, spatulate, 4–6 × 1.5–2.5 mm; anthers oblong, 0.5–0.6 mm. |
Fruiting pedicels | ascending, straight, (2.5–)4–11(–27) mm, glabrous or pubescent, trichomes 2–5-rayed or pectinate. |
horizontal to divaricate-ascending, straight, (4–)6–12(–15) mm, pubescent, trichomes 2–4-rayed. |
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. |
narrowly oblong to elliptic or oblong-lanceolate, often strongly twisted, flattened, 5–11 × 1.5–2.2 mm; valves pubescent, trichomes subsessile or sessile, 2–4-rayed, 0.07–0.3 mm; ovules 4–10(–12) per ovary; style (1)1.5–3(–4) mm, (sparsely pubescent). |
Seeds | oblong, 1.1–1.5 × 0.7–1 mm. |
oblong, 1.2–1.8 × 0.6–0.9 mm. |
2n | = 112. |
= 16. |
Draba incerta |
Draba ramosissima |
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Phenology | Flowering Jun–Aug. | Flowering Apr–Jun. |
Habitat | Rock outcrops, talus, gravelly areas, tundra | Limestone cliffs and outcrops, shale barrens, rocky wooded areas |
Elevation | 0-3300 m (0-10800 ft) | 0-1100 m (0-3600 ft) |
Distribution |
AK; CO; ID; MT; NV; UT; WA; WY; AB; BC; QC; YT
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DC; KY; MD; NC; TN; VA; WV |
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.) |
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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 | Alyssum dentatum, D. dentata, D. ramosissima var. glabrifolia |
Name authority | Payson: Amer. J. Bot. 4: 261. (1917) | Desvaux: J. Bot. Agric. 3: 186. (1815) |
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