This name is a synonym of Rumex trisetifer Stokes.
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 50136139) with original publication details: Monogr. Rumex 63, 75 1819.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:696987-1.
This name was in version 1 of The Plant List, record tro-50136139, and has not been changed.