Leaves of 2 types: laminate and filiform-dissected. Achenes 1.6-2 × 1-1.4 mm; beak 0.1-0.4 mm. 2 n = 48 (Europe).

Flowering spring-summer (Apr-Sep). Marshes, ditches, streams, ponds, and lakes; 0-2500 m; B.C., N.W.T.; Alaska, Calif., Idaho, Mont., Nev., Oreg., Utah, Wash., Wyo.; South America; Eurasia.

Plants growing in deep water may flower without producing floating leaves. Such plants cannot be distinguished from specimens of Ranunculus aquatilis var. diffusus except by culture in shallow water.