This name is a synonym of Sparganium angustifolium Michx..
The record derives from WCSP
(data supplied on 2012-03-26)
which reports it as a synonym (record 342129) with original publication details: Consp. Fl. Eur. Suppl. 2: 317 1890.
This name was in version 1 of The Plant List, record kew-342129.