This name is a synonym of Elymus elongatus (Host) Runemark.
The record derives from WCSP
(data supplied on 2012-03-23)
which reports it as a synonym (record 388413) with original publication details: Ess. Agrostogr. 102 1812.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:384970-1.
This name was in version 1 of The Plant List, record kew-388413.