This name is a synonym of Rumex japonicus Houtt..
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 26002561) with original publication details: Mém. Acad. Imp. Sci. Saint Pétersbourg, Sér. 7 12(2): 167 1868.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:697447-1.
This name was in version 1 of The Plant List, record tro-26002561, and has not been changed.