This name is a synonym of Symphyotrichum lateriflorum var. horizontale (Desf.) G.L.Nesom.
The record derives from TICA
(data supplied on 2012-02-11)
which reports it as a synonym (record E1FC7DC4-3A9F-4225-A8F5-2D29F2FA8964) with original publication details: 187 1884.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:23313-2.
This name was in version 1 of The Plant List, record gcc-24467.