This name is a synonym of Rheum rhizostachyum Schrenk.
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 50136520) with original publication details: Bull. Soc. Imp. Naturalistes Moscou 15: 422 1842.
This name was in version 1 of The Plant List, record tro-50136520, and has not been changed.