This name is a synonym of Penstemon incanus (A. Gray) Tidestr..
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 50240132) with original publication details: Syn. Fl. N. Amer. 2(1): 269 1878.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:187716-2.
This name was in version 1 of The Plant List, record tro-50240132, and has not been changed.