Ranunculus acris
Ranunculus macauleyi
acrid buttercup, bouton d'or, meadow buttercup, renoncule âcre, tall buttercup, tall crowfoot
Rocky Mountain buttercup
never tuberous.
slender, 0.7-1.3 mm thick.
erect from short caudex or rhizome, never rooting nodally, hispid, strigose, or glabrous, base not bulbous.
erect from short caudices, 6-15 cm, glabrous or sometimes pilose, each with 1-2 flowers.
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.
persistent, blades narrowly elliptic to lanceolate or oblanceolate, undivided, 1.5-4.5 × 0.5-1.1(-2.8) cm, base acute or long-attenuate, margins entire except for apex, apex truncate or rounded and 3(-5)-toothed.
receptacle glabrous;
sepals spreading, 4-6(-9) × 2-5 mm, hispid;
petals 5, yellow, 8-11(-17) × 7-13 mm.
pedicels glabrous or brown-pilose;
receptacle glabrous;
sepals 6-12 × 2.5-8 mm, abaxially densely brown-pilose;
petals 5(-8), 10-19 × 6-17 mm;
nectary scale glabrous.
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.
ovoid or cylindric, 5-10 × 4-5.5 mm;
achenes 1.5-1.7 × 1.2-1.3 mm, glabrous;
beak slender, straight or recurved, 0.5-1.5(-2.2) mm.
= 14.
Ranunculus acris
Ranunculus macauleyi
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.)
The type specimen of Ranunculus macauleyi var. brandegeei L. D. Benson, from the Sangre de Cristo Mountains, Colorado, differs from typical R. macauleyi in its tall stem, broad, crenate-laciniate leaves, and sepals with pale or transparent hairs. These characteristics are suggestive of R. inamoenus, and the plant may be of hybrid ancestry.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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