Ranunculus filiformis Michaux var. ovalis J. M. Bigelow, Fl. Boston. ed. 2, 224. 1824; R. flammula var. samolifolius (Greene) L. D. Benson; R. reptans Linnaeus var. ovalis (J. M. Bigelow) Torrey & A. Gray

Stems prostrate or sometimes ascending, 0.5-2 mm thick. Leaf blades lance-elliptic to lanceolate or linear, 0.8-3.3 × 0.2-0.8 cm. Flowers: sepals 2-3 mm; petals 3-5 × 2-3 mm. 2 n = 32.

Flowering spring-summer (May-Sep). Muddy ground or shallow water; 0-2900 m; Alta., B.C., Man., N.B., Nfld., N.W.T., N.S., Ont., P.E.I., Que., Sask.; Alaska, Ariz., Calif., Colo., Conn., Idaho, Maine, Mass., Mich., Minn., Mont., Nev., N.H., N.Mex., N.Y., N.Dak., Oreg., Pa., Utah, Vt., Wash., Wyo.

Ranunculus flammula var. ovalis , as currently understood, is heterogeneous. Many specimens from throughout the cited range scarcely differ from specimens of R . flammula var. reptans and perhaps should be included in the latter variety. Material from the Pacific slope, however, may be intermediate between R . flammula var. reptans and R . flammula var. flammula or may show various combinations of the distinguishing characteristics of the two. Biosystematic study of R . flammula as a whole will be needed for a meaningful treatment of these populations to be possible.