This name is a synonym of Rumex hymenosepalus Torr..
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 50079653) with original publication details: Bull. Torrey Bot. Club 25(10): 549 1898.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:224504-2.
This name was in version 1 of The Plant List, record tro-50079653, and has not been changed.