This name is a synonym of Penstemon attenuatus var. pseudoprocerus (Rydb.) Cronquist.
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 29204280) with original publication details: Mem. New York Bot. Gard. 1: 346–347 1900.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:187699-2.
This name was in version 1 of The Plant List, record tro-29204280.