This name is a synonym of Penstemon filiformis (D.D. Keck) D.D. Keck.
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 50338184) with original publication details: Man. Calif. Shrubs 517–518 1939.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:187574-2.
This name was in version 1 of The Plant List, record tro-50338184, and has not been changed.