Plants wholly submerged, producing terminal turions; lvs 1-3 cm, with filiform segments, all or many of the lvs alternate, subopposite, or irregularly scattered; fls axillary to foliage lvs; stamens 4; fr 2-2.5 mm, each mericarp with 2 low, denticulate or tuberculate, longitudinal ridges. N.S. and Que. to N.Y., w. to Minn.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.