45. Ranunculus abortivus Linnaeus, Sp. Pl. 1: 551. 1753.
Ranunculus abortivus subsp. acrolasius (Fernald) B. M. Kapoor & A. Löve; R. abortivus var. acrolasius Fernald; R. abortivus var. eucyclus Fernald; R. abortivus var. indivisus Fernald
Stems erect or nearly erect, 10-60 cm, glabrous, each with 3-50 flowers. Roots filiform, sometimes enlarged basally, 0.5-1.5 mm thick. Basal leaves persistent, blades reniform or orbiculate, undivided or sometimes innermost 3-parted or -foliate, 1.4-4.2 × 2-5.2 cm, base shallowly to deeply cordate, margins crenulate to crenate-lobulate, apex rounded to rounded-obtuse. Flowers: pedicels glabrous or nearly so; receptacle sparsely to very sparsely pilose; sepals 2.5-4 × 1-2 mm, abaxially glabrous; petals 5, 1.5-3.5 × 1-2 mm; nectary scale glabrous. Heads of achenes ovoid, 3-6 × 2.5-5 mm; achenes 1.4-1.6 × 1-1.5 mm, glabrous; beak subulate, curved, 0.1-0.2 mm. 2 n = 16.
Flowering late winter-summer (Mar-Jul). Woods, meadows, fallow fields, and clearings; 0-3100 m; St. Pierre and Miquelon; Alta., B.C., Man., N.B., Nfld., N.W.T., N.S., Ont., P.E.I., Que., Sask., Yukon; Ala., Alaska, Ark., Colo., Conn., Del., D.C., Fla., Ga., Idaho, Ill., Ind., Iowa, Kans., Ky., La., Maine, Md., Mass., Mich., Minn., Miss., Mo., Mont., Nebr., N.H., N.J., N.Mex., N.Y., N.C., N.Dak., Ohio, Okla., Pa., R.I., S.C., S.Dak., Tenn., Tex., Vt., Va., Wash., W.Va., Wis., Wyo.
Three varieties of Ranunculus abortivus are sometimes recognized. Plants from New England and the northern Appalachians often have thick stems and orbiculate leaves with narrow, deep basal sinuses; this form has been called R . abortivus var. eucyclus . Plants from southeastern Virginia may have the upper bracts merely lobed rather than deeply divided as is usual in R . sect. Epirotes ; those have been called R . arbortivus var. indivisus .
Native American tribes have used Ranunculus abortivus medicinally for a variety of purposes (D. E. Moerman 1986).