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 22ABE077-7061-41F2-BC65-1AF73429BD8F) with original publication details: Ill. Fl. N. U.S. 3 380 1898.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:23641-2.
This name was in version 1 of The Plant List, record gcc-14542.