This name is a synonym of Atriplex acanthocarpa subsp. stewartii (I.M.Johnston) J.Henrickson.
The record derives from WCSP (in review)
(data supplied on 2012-03-23)
which reports it as a synonym with original publication details: J. Arnold Arbor. 22: 110 1941.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:272948-2.
This name was in version 1 of The Plant List, record kew-2665826, and has not been changed.