Protologue Description: Var. crassior, var. nov., culmis 6-12 dm. altis, 3-5.5 mm. crassis; apice libero vaginae 1.5-8 cm. longo. 1.6-2 mm. latis.-Georgia to Texas, locally north to Massachusetts, Connecticut, New York, southern Ontario, Michigan, Wisconsin, Missouri and Oklahoma. Type in 3-8 dm. of water Waban Lak, Wellesley, Massachusetts, October 3, 1908, Fernald & Wiegand in Pl. Exsicc. Gray. no 133 (in Gray Herbarium).