Draba incerta |
Draba sphaeroides |
|
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whitlow-wort, Yellowstone Draba, Yellowstone Draba whitlow-wort, Yellowstone whitlow-grass, Yellowstone whitlow-wort |
ball 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 (branches often tangled with persistent leaf remnants, prostrate, slender, 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, (0.2–)0.3–0.8 dm, sparsely pubescent proximally, glabrous distally, trichomes usually 2- or 3-rayed, rarely some simple, 0.1–0.25 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. |
not rosulate; subsessile; petiole margins not ciliate; blade oblanceolate to oblong or elliptic, 0.3–0.8(–0.9) cm × (1–)1.5–3(–4) mm, margins entire, (not ciliate), surfaces usually pubescent, rarely both surfaces glabrous (except margin), with stalked, 2–4-rayed trichomes, 0.07–0.4 mm (or, rarely, trichomes mostly simple and 2-rayed adaxially). |
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. |
(3–)5–11(–14)-flowered, ebracteate, slightly elongated in fruit; rachis not flexuous, glabrous or sparsely 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 broadly ovate, 1.7–2.5 mm, glabrous or sparsely pubescent, (trichomes simple and short-stalked, 2- or 3-rayed); petals yellow, spatulate, 2.7–4 × 1.5–2.2 mm; anthers ovate, 0.4–0.5 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, (sometimes slightly expanded basally), 3–8 mm, usually glabrous, rarely sparsely pubescent, trichomes simple and 2- or 3-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. |
broadly lanceolate to ellipsoid or ovoid, plane, inflated at least basally, (2.5–)3.5–7(–8) × (1.5–)2–3.5 mm; valves glabrous or sparsely pubescent, trichomes simple and short-stalked, 2(–4)-rayed, 0.07–0.2 mm; ovules 4–10(–12) per ovary; style 0.3–1(–1.3) mm. |
Seeds | oblong, 1.1–1.5 × 0.7–1 mm. |
oblong, 1–1.5 × 0.8–1 mm. |
2n | = 112. |
= 20. |
Draba incerta |
Draba sphaeroides |
|
Phenology | Flowering Jun–Aug. | Flowering Jun–Aug. |
Habitat | Rock outcrops, talus, gravelly areas, tundra | Rock outcrops, talus, soil pockets on rocky slopes |
Elevation | 0-3300 m (0-10800 ft) | 2500-3300 m (8200-10800 ft) |
Distribution |
AK; CO; ID; MT; NV; UT; WA; WY; AB; BC; QC; YT
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NV |
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.) |
Of conservation concern. Draba sphaeroides is closely related to D. pedicellata; the two are easily distinguished using the characteristics discussed by M. D. Windham (2004). The species is known from Elko County (East Humboldt, Ruby and Jarbidge mountains) in northeastern Nevada. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 313. | FNA vol. 7, p. 339. |
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. oligosperma var. sphaeroides |
Name authority | Payson: Amer. J. Bot. 4: 261. (1917) | Payson: Amer. J. Bot. 4: 265. (1917) |
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