This name is a synonym of Sparganium eurycarpum subsp. coreanum (H.Lév.) C.D.K.Cook & M.S.Nicholls.
The record derives from WCSP
(data supplied on 2012-03-26)
which reports it as a synonym and as an invalid name (record 266096) with original publication details: Index Pl. Jap. 2: 23 1905.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:836772-1.
This name was in version 1 of The Plant List, record kew-266096.