This name is a synonym of Artemisia tridentata subsp. vaseyana (Rydb.) Beetle.
The record derives from TICA
(data supplied on 2012-02-11)
which reports it as a synonym (record B0CAD273-A869-4051-AFF9-68C15B750276) with original publication details: 384 1985.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:284977-2.
This name was in version 1 of The Plant List, record gcc-78268.