This name is a synonym of Penstemon crandallii subsp. glabrescens (Pennell) D.D. Keck.
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 50107891) with original publication details: Contr. U.S. Natl. Herb. 20(9): 375–376 1920.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:187433-2.
This name was in version 1 of The Plant List, record tro-50107891.