Dryas hookeriana |
Rosaceae subfam. Dryadoideae(synonym of Rosaceae subfam. dryadoideae) |
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Hooker's mountain-avens, mountain avens, white dryas, White Mountain-avens |
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Habit | Plants 1.5–9 cm. | Shrubs or trees. |
Leaves | blades usually oblong-elliptic to lanceolate, sometimes ovate, 4–16(–25) × 1–6(–10) mm, base usually truncate or cordate, sometimes cuneate, margins strongly revolute to flat, coarsely dentate or serrate, sinuses 5–25(–30)% to midvein, apex acute to obtuse, surfaces smooth to slightly plicate, only midvein ± obscured adaxially within medial fold, abaxial tomentose to woolly (obscuring lateral veins), adaxial usually glabrous, sometimes sparsely hairy proximally on midvein, feathery hairs usually absent, rarely 1+ on midveins abaxially, midveins and petioles abaxially stipitate-glandular. |
cauline; stipules present. |
Peduncles | 10–30 mm. |
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Flowers | erect at flowering; sepals lanceolate to narrowly elliptic, 4–10 × 0.6–1.5 mm; petals 8, spreading, usually white or cream, sometimes yellow, 9–14 × 5–11 mm; filaments glabrous. |
carpels 1–150, distinct, free, styles distinct; ovule 1. |
Fruits | achenes or aggregated achenes; styles persistent, elongate, usually plumose. |
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Achenes | 2.5–3 mm; styles 11–25 mm. |
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2n | = 18. |
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Dryas hookeriana |
Rosaceae subfam. Dryadoideae |
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Phenology | Flowering Jun–Aug. | |
Habitat | Alpine meadows, dry rocky slopes and ridges, alpine tundra | |
Elevation | 1500–3900 m [4900–12800 ft] | |
Distribution |
AK; CO; ID; MT; OR; UT; WA; WY; AB; BC; NT
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Discussion | In some states and provinces, the distribution of Dryas hookeriana is restricted to northwestern and central Colorado, southeastern and northernmost Idaho, western and central Montana, northeastern Utah (Uinta and Wasatch mountains), eastern Oregon and Washington, southwestern and central Wyoming, and western Northwest Territories. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
The subfamily consists of a single tribe. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 9, p. 329. | FNA vol. 9, p. 326. |
Parent taxa | ||
Sibling taxa | ||
Subordinate taxa | ||
Synonyms | D. octopetala var. angustifolia, D. octopetala subsp. hookeriana, D. octopetala var. hookeriana | |
Name authority | Juzepczuk: Izv. Glavn. Bot. Sada S.S.S.R. 28: 325. (1929) | Sweet: Brit. Fl. Gard., ser. 2, 1: sub plate 43. (1830) |
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