Lvs mostly 10-20 cm נ0.5-1.5 mm, ±erect, somewhat twisted, bright green to somewhat yellow-green, whitish toward the base, with stomates but without peripheral strands; sporangia 3-8 mm, pale or brown-dotted to wholly brown at maturity, to one-third covered by the velum; megaspores 0.35-0.65+ mm wide; beset with crowded tubercles and rough crests; 2n=44; perhaps an alloploid derived from nos. 1 [Iso쵥s engelmannii A. Braun] and 6 [Iso쵥s echinospora Durieu]. Amphibious (seldom in water over 0.6 m deep) in ponds, streams, and fresh or slightly brackish rivers, rooted in gravel or mud; s. Que., se. Ont., N. Engl., and e. N.Y. to W.Va. and S.C. (I. canadensis; I. dodgei; I. saccharata)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.