Ranunculus sceleratus L.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Stems erect, 2–6 dm, stout, hollow, glabrous, branched above and many-fld; basal and lower cauline lvs reniform, deeply 3-parted, the segments again cleft or lobed; upper lvs much smaller, commonly of 3 linear-oblong segments; pet 2–3 mm, shorter than the sep; achenes very numerous in a short-cylindric head, turgid, 0.8–1.2 mm, marginless, and very nearly beakless; 2n=32. Marshes, ditchbanks, and swampy meadows; circumboreal, in Amer. s. to Va., Mo., N.M., and Calif. Apr.–Aug. Our common phase, with minute, irregular transverse ridges on the central part of each face of the achene, is the widespread var. sceleratus. The chiefly western Amer. var. multifidus Nutt., with the basal lvs usually deeply twice cleft, and with the achene-surfaces smooth except for a circle of minute pin-prick depressions on each face, extends e. to Minn. and Io.