This name is a synonym of Physaria didymocarpa subsp. lanata (A. Nelson) O'Kane.
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 50067015) with original publication details: Bull. Torrey Bot. Club 31(5): 241 1904.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:195567-2.
This name was in version 1 of The Plant List, record tro-50067015, and has not been changed.