Stems ascending or reclining, 5-10 dm; lvs broadly cordate, 5-10 cm long and wide, blunt to subacute, pale beneath, the broadly rounded basal auricles somewhat incurved below the rounded sinuses; fls in small axillary fascicles, the yellow perianth nearly straight, 3 cm, enlarged around the ovary, terminating in an ovate lobe on one side; 2n=14. Native of s. Europe, occasionally escaped from cult. in our range. Summer.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.