This name is a synonym of Cynanchum densiflorum W.D.Stevens.
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 2600589) with original publication details: Bot. Jahrb. Syst. 37: 618 1906.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:176858-2.
This name was in version 1 of The Plant List, record tro-2600589.