This name is a synonym of Rumex aquaticus subsp. arcticus (Trautv.) Hiitonen.
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 50118286) with original publication details: Fl. Bor.-Amer. 2: 129 1840.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:224420-2.
This name was in version 1 of The Plant List, record tro-50118286, and has not been changed.