This name is a synonym of Penstemon floridus var. austinii (Eastw.) N.H. Holmgren.
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 29204310) with original publication details: Bull. Torrey Bot. Club 32(4): 206 1905.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:187182-2.
This name was in version 1 of The Plant List, record tro-29204310.