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 B9EDA656-0F24-493E-9470-6A07252ABD78) with original publication details: 102 1985.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:272707-2.
This name was in version 1 of The Plant List, record gcc-53943.