Both the foliage and flowers of Large-Flowered Penstemon are beautiful and distinctive. Unfortunately, the blooming period of the flowers is rather short, but you can't have everything. Because of its distinctive bluish foliage and large flowers (up to 2" in length), this species is easy to distinguish from other Penstemon spp. that are native to Illinois. However, a non-native species from the west, Penstemon cobaea (Showy Penstemon), is somewhat similar in appearance and its flowers are equally large in size. Unlike Large-Flowered Penstemon, this latter species has pubescent stems, while its upper leaves and bracts have bases that are sessile, rather than clasping. Showy Penstemon has naturalized in Kane County, Illinois.