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 2C79674E-46B6-4BF4-8444-4A50F5BF3E66) with original publication details: 402 1829.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:311162-2.
This name was in version 1 of The Plant List, record gcc-40059.