Plants 2-4 dm; blades of basal lvs broadly ovate to subrotund, 1-3 cm, 3/4 to fully as wide, at base broadly rounded to more often cordate, not decurrent; cauline lf as large as the basal, broadly ovate, sessile and cordate-clasping; pet 5-17-nerved, 9-13 mm, half longer to twice as long as the lance-triangular green sep; staminodes green or yellow, 5-9 mm, dilated to an obovate or reverse-triangular scale with 9-23 short, slender filaments on the distal margin; 2n=18, 27, 36, 54. Calcareous shores and wet meadows; circumboreal, s. in Amer. to Nf., Mich., Minn., Wyo., and B.C.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.