This name is a synonym of Rumex stenophyllus Ledeb..
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 50118550) with original publication details: Trans. Kansas Acad. Sci. 53: 186–189, f. s.n. [p. 187] 1950.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:224394-2.
This name was in version 1 of The Plant List, record tro-50118550, and has not been changed.