This name is a synonym of Apocynum androsaemifolium var. incanum A.DC..
The record derives from WCSP
(data supplied on 2012-03-23)
which reports it as a synonym (record 12908) with original publication details: Methodus 464 1794.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:77208-1.
This name was in version 1 of The Plant List, record kew-12908.