Submersed lvs chiefly alternate, subopposite, or irregularly scattered; whorled lvs also present; no turions; fls axillary to submersed foliage lvs or in short emersed spikes; bracts mostly alternate, longer than the fls, irregularly pinnately parted, varying to linear and entire; mericarps 0.7-1.2 mm, obliquely truncate, rounded on the back, smooth or nearly so. N.S. and Vt. to Md., w. locally to Ill. and Minn.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.