This name is a synonym of Amaranthus powellii S.Watson.
The record derives from WCSP (in review)
(data supplied on 2012-03-23)
which reports it as a synonym with original publication details: Naturaliste Canad. 93: 641 1966.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:10699-2.
This name was in version 1 of The Plant List, record kew-2633065, and has not been changed.