This name is a synonym of Magnolia acuminata var. subcordata (Spach) Dandy.
The record derives from WCSP
(data supplied on 2012-03-23)
which reports it as a synonym (record 117522) with original publication details: Fl. Bor.-Amer. 1: 328 1803.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:149278-2.
This name was in version 1 of The Plant List, record kew-117522, and has not been changed.