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 50118289) with original publication details: Prodr. 14(1): 44 1856.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:224451-2.
This name was in version 1 of The Plant List, record tro-50118289, and has not been changed.