Penstemon rubicundus
In unveiling this striking species, Keck suggested a possilble hybrid ancestry involving P. palmeri, which approaches the Wassuk Range 60 km from the north, and P. floridus, which approaches the area 40 km from the south. Keck's hypothesis seems probable. In many of its characters P. rubicundus resembles one or the other species, and the corolla size and shape, an important characteristic of the Spectabiles species, is intermediate between the two. An interesting specimen from Chiatovich Creek in the White Mountains appears to be intermediate between P. rubicundus and P. floridus. It is from within the range of P. floridus var. floridus.
Holmgren NH. 1984. Penstemon and Keckiella. In Intermountain Flora, vol. 4. Ed. Arthur Cronquist et al. Bronx: The New York Botanical Garden.