Ranunculus hyperboreus
Ranunculus acris
arctic buttercup, far-northern buttercup, high northern buttercup, renoncule hyperboréale
acrid buttercup, bouton d'or, meadow buttercup, renoncule âcre, tall buttercup, tall crowfoot
never tuberous.
prostrate, glabrous, rooting nodally.
erect from short caudex or rhizome, never rooting nodally, hispid, strigose, or glabrous, base not bulbous.
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.
blades pentagonal in outline, deeply 3-5-parted, 1.8-5.2 × 2.7-9.8 cm, segments 1-2x-lobed or -parted, ultimate segments narrowly elliptic or oblong to lanceolate, margins toothed or lobulate, apex acute to rounded.
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.
receptacle glabrous;
sepals spreading, 4-6(-9) × 2-5 mm, hispid;
petals 5, yellow, 8-11(-17) × 7-13 mm.
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.
globose, 5-7(-10) mm wide;
achenes 2-3 × 1.8-2.4 mm, glabrous, margin forming narrow rib 0.1-0.2 mm wide;
beak persistent, deltate, usually with tip short or long, straight or curved, subulate, 0.2-1 mm.
= 32.
= 14.
Ranunculus hyperboreus
Ranunculus acris
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.)
Ranunculus acris is variable in form and division of leaves, size of achene beak, and form of indument on the proximal stem. Most North American plants are weedy and have poorly differentiated caudices; these forms probably were introduced from Eurasia. Rhizomatous plants with large flowers (parenthetic measurements above) found in the Aleutian Islands of Alaska and in Greenland are probably native. Aleutian populations of this form have been called R. acris var. frigidus Regel or R. grandis Honda var. austrokurilensis (Tatewaki) H. Hara. Both names were originally applied to Asiatic plants, and their applicability to American specimens is open to question.
Some Native American tribes used Ranunculus acris as an analgesic, a dermatological or oral aid, an antidiarrheal, antihermorrhagic, and a sedative (D. E. Moerman 1986).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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