This name is a synonym of Penstemon eatonii subsp. exsertus (A. Nelson) D.D. Keck.
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 50102527) with original publication details: Amer. J. Bot. 18(6): 438 1931.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:187385-2.
This name was in version 1 of The Plant List, record tro-50102527.