Flora of North America species comparison

Welsh described var. desereticus based on material with relatively larger corollas (15–19 mm) and smaller basal leaves (8–25 × 2–6 mm) from mountain ranges in the western Bonneville Basin of Utah; E. C. Neese and N. D. Atwood (2003) considered the variety to be limited to Utah. Variety desereticus appears to be confluent with a form of the species in the Calcareous Mountains of eastern Nevada, which N. H. Holmgren (1984) discussed and later recognized as Penstemon decurvus (Holmgren 2017). Penstemon decurvus, described from eastern Lincoln County, Nevada, also is referable here. Plants from northeastern California, extreme southwestern Idaho, extreme northwestern Nevada, and eastern and central Oregon often have cinereous leaves and relatively longer stems, shorter calyx lobes, and, sometimes, more open inflorescences; these plants have been called P. cinereus. This element grades into other phases to the east and appears to be another form of highly variable var. humilis. Some specimens from eastern Idaho (Clark and Fremont counties) have glabrous leaves, possibly from genetic exchange with P. aridus.

(Discussion copyrighted by Flora of North America; reprinted with permission.)