Ranunculus acris
Ranunculus pusillus
acrid buttercup, bouton d'or, meadow buttercup, renoncule âcre, tall buttercup, tall crowfoot
low buttercup, low spearwort, weak buttercup
never tuberous.
not thickened basally, glabrous.
erect from short caudex or rhizome, never rooting nodally, hispid, strigose, or glabrous, base not bulbous.
erect or ascending, rooting at most proximal nodes, glabrous.
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.
ovate or lanceolate, 1.2-4.2 × 0.5-1.2 cm, base acute to truncate, margins entire or denticulate, apex acuminate to rounded.
bracts linear to lanceolate or oblanceolate.
receptacle glabrous;
sepals spreading, 4-6(-9) × 2-5 mm, hispid;
petals 5, yellow, 8-11(-17) × 7-13 mm.
receptacle glabrous;
sepals 4-5, spreading or reflexed from base, 1.5-3 × 1-1.5 mm, glabrous or sparsely hirsute;
petals 1-3, 1.5-2 × 0.5-1 mm;
nectary scales 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.
hemispheric to cylindric, 2-8 × 2-3 mm;
achenes 1-1.2 × 0.6-0.8 mm, ± tuberculate, glabrous;
beak absent or nearly so, to 0.1 mm.
= 14.
Ranunculus acris
Ranunculus pusillus
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.)
In most specimens of Ranunculus pusillus, the heads of achenes are hemispheric to short-ovate and only 2-3 mm. Occasional plants with cylindric heads of achenes 4-6 mm from the Gulf Coast states have been called R. pusillus var. angustifolius.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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