Draba incerta |
Draba mulliganii |
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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; (cespitose); caudex branched (with persistent leaves); often 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, 0.3–1.2 dm, glabrous throughout or sparsely pubescent proximally, trichomes short-stalked, 4–10-rayed, (non-crisped). |
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; subsessile or shortly petiolate (petiolar base and proximal margin ciliate with stiff, subsetiform, simple trichomes, 0.3–0.6 mm); blade oblanceolate or lanceolate, 5–9 × 1–2 mm, margins entire, surfaces usually pubescent, abaxially with short-stalked, 8–12-rayed, stellate, (non-crisped) trichomes, 0.1–0.3 mm (often without spurred rays), rarely glabrescent, trichomes confined to margin, (midvein and petiole not thickened), adaxially with similar stellate and some simple trichomes. |
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. |
3–11-flowered, ebracteate, elongated in fruit; rachis not flexuous, glabrous. |
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 (caducous), ovate, 1.7–2.2 mm, pubescent subapically, (trichomes simple and 2-rayed); petals white, broadly obovate, 3.2–4 × 2–3 mm, (apex obtuse); anthers ovate, 0.4 mm. |
Fruiting pedicels | ascending, straight, (2.5–)4–11(–27) mm, glabrous or pubescent, trichomes 2–5-rayed or pectinate. |
divaricate to ascending (not appressed to rachis), straight, (4–)5–9 mm, glabrous. |
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. |
ovate-lanceolate to oblong, not twisted, flattened, 5–8 × 2–2.5 mm; valves glabrous; ovules 12–16 per ovary; style 0.4 1 mm. |
Seeds | oblong, 1.1–1.5 × 0.7–1 mm. |
ovoid, 0.7–1.1 × 0.5–0.6 mm. |
2n | = 112. |
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Draba incerta |
Draba mulliganii |
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Phenology | Flowering Jun–Aug. | Flowering Jun–Jul. |
Habitat | Rock outcrops, talus, gravelly areas, tundra | Limestone gravel around outcrops, limestone crevices, dry serpentine knolls in heath vegetation with patches of exposed slide rock, shale rubble slopes |
Elevation | 0-3300 m (0-10800 ft) | 300-1600 m (1000-5200 ft) |
Distribution |
AK; CO; ID; MT; NV; UT; WA; WY; AB; BC; QC; YT
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AK |
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. 321. |
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) | Al-Shehbaz: Harvard Pap. Bot. 14: 85. (2009) |
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