Ranunculus hyperboreus |
Ranunculus arizonicus |
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arctic buttercup, far-northern buttercup, high northern buttercup, renoncule hyperboréale |
Arizona buttercup |
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Stems | prostrate, glabrous, rooting nodally. |
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Leaves | basal leaves absent, cauline leaf blades reniform to broadly flabellate, deeply 3-lobed or 3-parted, 0.3-1.2 × 0.5-2.1 cm, base obtuse to cordate, lobes undivided or lateral lobes cleft, terminal segment entire or distally crenulate, apex rounded. |
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Flowers | receptacle glabrous; sepals 3-4, spreading or reflexed from base, 2-4 × 1-3 mm, glabrous; petals 3-4, 2-4 × 1-3 mm; nectary on petal surface, scale poorly developed and forming crescent-shaped ridge surrounding but not covering nectary; style 0.1-0.2 mm. |
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Heads of achenes | globose or short-ovoid, 3-5 × 2-5 mm; achenes 1-1.4 × 0.8-1.2 mm, glabrous; beak linear, curved, 0.1-0.4 mm. |
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2n | = 32. |
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Ranunculus hyperboreus |
Ranunculus arizonicus |
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Phenology | Flowering late spring–summer (Jun–Aug). | |
Habitat | Floating in shallow water or stranded on exposed mud at margins of streams and ponds and open wet soil and marshes, in tundra or boreal or subalpine forest | |
Elevation | 0-3400 m (0-11200 ft) | |
Distribution |
AK; CO; ID; MT; NV; UT; WY; AB; BC; MB; NF; NT; ON; QC; SK; YT; Greenland; Eurasia
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AZ; NM; Mexico
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Discussion | Specimens of Ranunculus hyperboreus from the central and southern Rocky Mountains have the leaves always cordate and the fruiting heads always 4-5 mm; they have been separated as R. hyperboreus subsp. intertextus. Although Arctic specimens are more variable, they often have shallowly cordate leaf bases and equally large heads of achenes, so segregation of the subspecies seems inappropriate. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Varieties 2 (1 in the flora). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 3. | FNA vol. 3. |
Parent taxa | Ranunculaceae > Ranunculus > subg. Ranunculus > sect. Hecatonia | Ranunculaceae > Ranunculus > subg. Ranunculus > sect. Epirotes |
Sibling taxa | ||
Subordinate taxa | ||
Synonyms | R. hyperboreus subsp. arnellii, R. hyperboreus subsp. intertextus, R. hyperboreus var. samojedorum, R. hyperboreus var. tricrenatus, R. hyperboreus var. turquetilianus, R. natans var. intertextus | |
Name authority | Rottbøll: Skr. Kiøbenhavnske Selsk. Laerd. Elsk. 10: 458. (1770) | Lemmon ex A. Gray: Proc. Amer. Acad. Arts 21: 370. (1886) |
Web links |