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).
From Flora of Indiana (1940) by Charles C. Deam
This buttercup is frequent to common throughout the state and is found in all kinds of habitats except in very sandy or very wet places. Where clean cultivation is desired in lawns, orchards, and elsewhere, it is a pernicious weed.
Stems erect, branched above, 2-5 dm, glabrous or sometimes puberulent above; basal lvs reniform to rotund, ±cordate at the base, chiefly merely crenate, but one or more of them often variously lobed or divided; cauline lvs sessile or subsessile, usually deeply 3-5-divided, the segments varying from broadly linear and entire to oblanceolate or even obovate and irregularly toothed or incised; pet 2-3 mm, rhombic, shorter than the sep; achenes in a short-ovoid head on a villous receptacle, broadly obovate, turgid, 1.5 mm, the beak very short; 2n=16. Moist or dry woods, abundant and variable; Lab. to Alas., s. to Fla., Tex., and Colo. Apr.-June. The var. eucyclus Fernald, with slender, flexuous stems and suborbicular, deeply cordate basal lvs with narrow sinus, occurs chiefly from N.Y. and N. Engl. to Nf. and Que. Var. abortivus, stouter and more erect, not markedly flexuous, with more reniform basal lvs with a broad sinus, is mostly but not entirely more southern than var. eucyclus. Other described vars. are of doubtful significance.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.