Ranunculus pensylvanicus L.f.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Spreading-hairy annual or perennial, erect, simple or branched, 3–7 dm; basal lvs soon withering, cauline few, petioled; lf-segments 3, the terminal one stalked, all deeply 3-lobed, the lobes toothed or incised; fls few, short-pedicellate; pet obovate, 2–4 mm, shorter than the reflexed sep; anthers 0.7–1 mm; achenes in a cylindric or ovoid-cylindric head mostly 10–15 mm, subrotund, 1.8–2.7 mm, sharply margined; beak flat-subulate, 0.6–1.4 mm, straight or curved; 2n=16. Marshes, ditchbanks, and wet meadows; Nf. to Alas. and e. Asia, s. to N.J., Pa., O., n. Ind., n. Ill., Minn., and Ariz. July, Aug.