This name is a synonym of Aristida mollissima subsp. argentea (Schweick.) Melderis.
The record derives from WCSP
(data supplied on 2012-03-23)
which reports it as a synonym (record 394387) with original publication details: Bot. Jahrb. Syst. 76: 218 1954.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:389245-1.
This name was in version 1 of The Plant List, record kew-394387, and has not been changed.