This name is a synonym of Rumex crispus subsp. uliginosus (Le Gall) Akeroyd.
The record derives from WCSP (in review)
(data supplied on 2012-03-23)
which reports it as a synonym with original publication details: Fl. Morbihan 500 1852.
This name was in version 1 of The Plant List, record kew-2869537, and has not been changed.