Species in the genus Penstemon are commonly called penstemons or beardtongues in English, and they will often have a common name based on either. As the subgenuses have some taxonomic uncertainty, the species are arranged alphabetically by name in the lists. , there are species and seven natural hybrids, according to Plants of the World Online (POWO). The database World Flora Online (WFO) regards all the species listed by POWO as valid, but additionally lists two natural hybrids as species and four additional species as valid.
These species of Penstemon are considered valid by both World Flora Online (WFO) and Plants of the World Online (POWO), with the exception of Penstemon grandiflorus. In both POWO and WFO, it is regarded as a synonym of Penstemon bradburyi. However, P. grandiflorus continues to be widely used as the correct species name in North America, including by the Flora of North America and the USDA Natural Resources Conservation Service PLANTS database (PLANTS). It is listed as P. grandiflorus in the table with the synonym noted.
these seven naturally occurring hybrids are valid, according to POWO. Two are considered valid species, according to WFO.
These four species are listed as accepted by World Flora Online, but are not accepted by Plants of the World Online.