Plant of the Week
Range map of large beardtongue. States are colored green where the species may be found.
The purple streaks in the throat of the flowers of large beardtongue are nectar guides for pollinating insects. Photo by Charlie McDonald.
The flower stalks of large beardtongue, which may be up to 3½ tall, will each have 4 to 6 flower clusters with each cluster subtended by a pair of leaves. Photo by Charlie McDonald.
Large beardtongue (Penstemon grandiflorus)
By Charlie McDonald
When botanists gave Penstemon grandiflorus its scientific name, they really got it right! The Latin term “grandiflorus” means “large- or grand-flowered”, which is really a perfect description for the large beardtongue. This beauty is 1 to 3½ feet tall and unbranched, except at the base, where several stems may arise from a thick rootstock. The leaves are blue-gray or blue-green with smooth margins and have a rather succulent appearance. They decrease in size as you go up the stem with the upper leaves often clasping the stem. The flowers are up to 2 inches long. Unlike most other penstemons, the flower has no sterile stamen that is bearded.
The large beardtongue is most common in dry sandy or gravelly soils in prairies of the northern Great Plains and is less frequent in prairies further south. It blooms in late spring to early summer.
The genus Penstemon is in the figwort family (Scrophulariaceae). There are over 250 species in the genus with most of them native to the American west. Most species have large attractive flowers of blue, purple, or lavender, but pink, white and even red species also occur. Penstemons are so popular that there is even an organization, The American Penstemon Society, devoted exclusively to the appreciation and cultivation of these plants.