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 C6ABF5AA-0DF7-4419-9C97-6A8E4F6A8864) with original publication details: 166 .
This name was in version 1 of The Plant List, record gcc-79024, and has not been changed.