Stems nearly erect, hispid, base not bulbous. Basal and lower cauline leaf blades ovate to cordate, 3-foliolate, 2-6 × 2-6 cm, leaflets again parted, leaflet base truncate to acute, margins crenate-dentate to crenate-lobulate, apex rounded to obtuse. Flowers pedicellate; receptacle pilose; sepals 5, reflexed, 3-8 × 1.5-3 mm, pilose; petals 5, 7-10 × 4-8 mm. Heads of achenes globose or ovoid, 5-8 × 6-7 mm; achenes 15-35 per head, 2-3 × 2-3 mm, faces sparsely papillate or sometimes smooth, glabrous, margin smooth; beak oblong to deltate, curved, 0.4-0.7 mm. Flowering late winter-summer (Mar-Aug). Roadsides, fields, open woods; 0-200 m; introduced; B.C.; Ala., Ark., Calif., Fla., Ga., Ill., Kans., Ky., La., Md., Miss., Mo., N.J., N.Y., N.C., Okla., Oreg., Pa., R.I., S.C., Tenn., Tex., Va.; native to Europe; Pacific Islands; Australia. Ranunculus sardous was collected in New Brunswick and Ontario in the 1800s, but it apparently has not persisted in those provinces.
Annual, usually several-stemmed, 1-6 dm, much branched above; principal lvs mostly clustered near the base, 3-parted, the terminal segment stalked, all segments broadly triangular-obovate, deeply lobed and incised; cauline lvs much smaller, with fewer and narrower segments; fls numerous, long-pedicellate; pet 5-8(-10) mm; receptacle hairy in fr; achenes 30-40, broadly obovate to subrotund, the margin smooth and sharply differentiated, the sides papillate; beak 0.2-0.5 mm; 2n=16, 48. Native of Europe, found here and there in our range as a weed. May-July.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.