Penstemon humilis var. humilis
Penstemon humilis is a complex species. There seems to be a different race in nearly every section of the region in which it occurs. In the Great Basin there are four or five feebly marked geographic races exhibiting tendencies too vague to merit taxonomic recognition. In the high mountains of the Calcareous Mountains Section of eastern Nevada is a form that is usually low in stature with small leaves but relatively large flowers. In the lower mountains of the southern Calcareous Mountains Section is a form with larger than usual flowers that has been called P. decurvus Pennell ex Crosswh. In the mountains of Tonopah Section of south-central Nevada is a robust race with larger than usual basal leaves. Ranging across the northern half of the Basin is the more typical phase exhibiting a gradient from the sparsely puberulent plants associated with the type of the species in the eastern portion to the cinereous-pubescent phase associated with the name P. cinereus Piper in the western portion.
Holmgren NH. 1984. Penstemon and Keckiella. In Intermountain Flora, vol. 4. Ed. Arthur Cronquist et al. Bronx: The New York Botanical Garden.