Isoetes virginica N.Pfeiff.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Lvs 15–30 cm × 0.5 mm, recurved, somewhat twisted, commonly brown toward the base, with abundant stomates and 4 or more peripheral strands; sporangia broadly oblong, 3–5 mm, brown at maturity, one-fourth covered by the velum; megaspores 0.4–0.5 mm wide, provided with short, low ridges. Amphibious on clay soils in temporary pools, often over sandstone; rare and sporadic from Va. to S.C., mainly on the Piedmont.