This name is a synonym of Apocynum × floribundum Greene.
The record derives from WCSP
(data supplied on 2012-03-23)
which reports it as a synonym (record 329918) with original publication details: Rep. (Annual) Michigan Acad. Sci. 17: 170 1916.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:16618-2.
This name was in version 1 of The Plant List, record kew-329918.