This name is a synonym of Atriplex argentea var. caput-medusae (Eastw.) Fosberg.
The record derives from WCSP (in review)
(data supplied on 2012-03-23)
which reports it as a synonym with original publication details: Proc. Calif. Acad. Sci. II, 6: 316 1896.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:272922-2.
This name was in version 1 of The Plant List, record kew-2665136, and has not been changed.