This name is a synonym of Rumex longifolius DC..
The record derives from WCSP (in review)
(data supplied on 2012-03-23)
which reports it as a synonym with original publication details: Handb. Skand. Fl. 148 1820.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:697061-1.
This name was in version 1 of The Plant List, record kew-2423921, and has not been changed.