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 266183) with original publication details: Fl. Wermland 259 1859.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:836801-1.
This name was in version 1 of The Plant List, record kew-266183.