This name is a synonym of Penstemon pachyphyllus var. congestus (M.E. Jones) N.H. Holmgren.
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 50079698) with original publication details: Ann. Carnegie Mus. 26: 331 1937.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:187303-2.
This name was in version 1 of The Plant List, record tro-50079698.