This name is a synonym of Mimulus floribundus var. geniculatus (Greene) A.L. Grant.
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 50102142) with original publication details: Bull. Calif. Acad. Sci. 1: 280 1885.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:805945-1.
This name was in version 1 of The Plant List, record tro-50102142, and has not been changed.