This name is a synonym of Rhododendron roxieanum var. cucullatum (Hand.-Mazz.) D.F. Chamb..
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 12304741) with original publication details: Notes Roy. Bot. Gard. Edinburgh 13(65): 248–249 1922.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:332211-1.
This name was in version 1 of The Plant List, record tro-12304741, and has not been changed.