This name is a synonym of Artemisia ludoviciana subsp. candicans (Rydb.) D.D.Keck.
The record derives from TICA
(data supplied on 2012-02-11)
which reports it as a synonym (record 33F90A21-25A3-4342-9053-E96F54BAC334) with original publication details: 556 1956.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:20681-2.
This name was in version 1 of The Plant List, record gcc-69834, and has not been changed.