Rhizome elongate, becoming stout and scaly; stolons wanting; lvs reniform to reniform-cordate, distantly crenate-serrate, rounded above or shortly blunt-tipped, variously hairy on both sides, or on the lower surface only, or wholly glabrous; fls 7-10 mm wide; sep narrowly lanceolate; pet white, all beardless or bearded, the 3 lower with brown-purple veins near the base, the spur short and rounded; frs ellipsoid, 4-5 mm, the cleistogamous ones on horizontal to erect peduncles; seeds brown with darker marks; 2n=24. Arbor-vitae swamps and cold woods; Nf. to B.C., s. to Mass., Conn., N.Y., Mich., Minn., and Colo. May-July.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.