This name is a synonym of Penstemon palmeri var. macranthus (Eastw.) N.H. Holmgren.
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 29204314) with original publication details: Bull. Torrey Bot. Club 32(4): 207 1905.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:187470-2.
This name was in version 1 of The Plant List, record tro-29204314.