Delicate, fibrous-rooted perennial; lvs linear, to 5 cm; staminate pedicels to 4 cm; sep 2.5-4 mm, lanceolate; achenes cylindric, 2 mm, half as wide; 2n=24. Sandy shores or shallow water; Nf. and Que. to Ont. and n. N.Y.; also in Wis., Minn., and Europe. Summer. Only emersed plants flower. American plants are slightly smaller than the European, and may be distinguished as var. americana (Fernald) Gleason.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.