This name is a synonym of Symphyotrichum laeve var. purpuratum (Nees) G.L.Nesom.
The record derives from TICA
(data supplied on 2012-02-11)
which reports it as a synonym (record 43465942-2C31-49C3-A5A3-0742DF42F9FE) with original publication details: Companion Bot. Mag. 1 97 1835.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:329036-2.
This name was in version 1 of The Plant List, record gcc-3908, and has not been changed.