I have found this species in artificial ponds in hard, white clay soil in three counties, and in low woods in similar soil but richer in humus in Harrison County. The colony in Floyd County is on the east side of the road south of Martinsburg in an old mill pond on the Philip McGuirk farm. It is abundant here and of large size.
Lvs 6-35(-50) cm נ0.6-2 mm, erect, not twisted, with abundant stomates and usually 4 peripheral strands; sporangia 6-13 mm, pale, one-third to two-thirds covered by the velum; megaspores 0.35-0.6 mm wide, raised-reticulate; 2n=22. Amphibious, submersed in spring, usually later emersed; N.H. to Fla., w. to Ind., Ill., se. Mo., and Miss.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.