This name is a synonym of Asclepias incarnata subsp. pulchra (Ehrh. ex Willd.) Woodson.
The record derives from WCSP (in review)
(data supplied on 2012-03-23)
which reports it as a synonym with original publication details: Rhodora 23: 288 1922.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:21205-2.
This name was in version 1 of The Plant List, record kew-2654861, and has not been changed.