On the wet, sandy borders of lakes and sloughs. [Variety setosus has bristles present around the achene. It is] found in habitats similar to those in which the species [Schoenoplectus smithii] is found. [Schoenoplectus smithii] is difficult to separate from Scirpus debilis [=Schoenoplectus purshianus]. In fact, they are united in Britton and Brown, Illustrated Flora, ed. 2. The shape of the stem seems to be the only constant character. The divaricating bract of Scirpus debilis is very characteristic but it seems that all plants do not have a divaricating bract. The shape of the achene can not be relied upon since on the same plant one can find plano-convex as well as biconvex achenes.