This name is a synonym of Aster ageratoides var. laticorymbus (Vaniot) Hand.-Mazz..
The record derives from TICA
(data supplied on 2012-02-11)
which reports it as a synonym (record 0BB9206B-3C2B-4925-B9F7-B377444E066E) with original publication details: 1903.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:181573-1.
This name was in version 1 of The Plant List, record gcc-111600, and has not been changed.