This name is a synonym of Penstemon heterophyllus subsp. spinulosus (Wooton & Standl.) D.D. Keck.
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 50110124) with original publication details: Contr. U.S. Natl. Herb. 16(4): 173 1913.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:187790-2.
This name was in version 1 of The Plant List, record tro-50110124.