If you have one of those sites in your garden where nothing seems to grow, consider sticking some penstemons in there and let the praises flow.
If you are a gardener or plant enthusiast living in the West, you probably know of penstemons. Colorful herbaceous wildflowers, evergreen shrubs, or woody “shrublets,” penstemons predominately grow in the western US, but of the 280 or so species, there are a small percentage that are native to the East. However, the genus is represented by plants that grow from throughout North America.
The naming convention surrounding this variety of plant hasn't always been the most clear. The first scientific description of penstemons was published in 1748 by John Mitchell, an Anglo-American botanist and physician. He used the name to describe the hairy beardtongue, Penstemon hirsutus, or the eastern smooth beardtongue, P. laevigatus, two species that range over much of the eastern U.S.
Mitchell aside, there is some confusion and disagreement over the origin of the name "pentsemon." Some believe the name means “five stamens,” even though one of the stamens is sterile and lacks an anther. Others believe the name means “almost stamen” in reference to this sterile stamen. The name “beardtongue” is often substituted for pentsemon and is in reference to the hairs on one of the stamens and the way that stamen is arranged in the bottom of the flower’s throat. However, the large beardtongue, P. grandiflorus, which grows throughout the Midwest, lacks this identifier.
To add to the confusion, Carl von Linnaeus the Father of Plant Systematics, published Mitchell’s description as Chelone pentstemon, referring to this fifth stamen. Fortunately, the genus eventually reversed back to Penstemon, ending the debate, and it continues to remain in use today.
So let the praises begin!
Most penstemons bloom in late spring, but others bloom throughout the summer, especially at higher elevations. Their tubular-shaped flowers range from white to scarlet, depending upon the species, and vary from short, a quarter-inch long, to several inches in length. The flowers attract a variety of pollinators, from bumblebees to butterflies and hummingbirds, whose long proboscis is able to reach deep into the throat of the flower for its nectar rewards.
In my garden I grow a number of penstemons for color and attracting pollinators. The long, wands of Palmer’s penstemon flowering stalks produce large, but short, tubular flowers that attract bees. I love watching as the bumblebees plow into the flowers in search of pollen and work their way up the scapes, visiting each flower. I also grow several species with red flowers—the Eaton’s penstemon and the fiery-red scarlet bugler, P. barbatus—for hummingbirds that nest in the neighborhood or are on their southern migration.
Of course, here at my home in Central Oregon, the deer like to chomp on the developing flowering stalks, often when the stalks are young and the flowers are getting set to bloom. However, seems that once the plants bloom, the deer leave them alone and look for other vegetation. The plants are also generally insect- and pest-free, and can tolerate that freak summer hail storm which might otherwise shred more delicate flora.
Penstemons may be found in many states and Canadian provinces, from arid deserts to mountain meadows. They grow in a variety of soil types, but some can be more restricted, such as the endangered Peck’s pentsemon only found in moist meadows in parts of Oregon or other species that grow only in disturbed rocky sites. This pioneering habit makes some species like the Palmer’s pentsemon, Penstemon palmeri, or Eaton’s pentsemon, Penstemon eatonii, good candidates for roadside reclamation projects. The plants do well in full-sun and in fast-draining soils made up of volcanic ash.
The drought-tolerant nature of this plant has advanced its distribution from the wild to cultivated landscapes and rock gardens. Though some species may be short lived, others, once established, will thrive with little more than appreciative glances. This tendency to do well in ordinary garden soil, provided that it’s kept on the drier side, has elevated species like the Rocky Mountain pentsemon, Penstemon strictus, to be a common nursery plant.
Another feature of penstemons is they self-seed, especially if gardeners can leave their flowering stalks up through the fall and early winter(leaving a few stalks in place also helps protect the basal vegetation). The flower’s thick capsule likes a bit of roughhousing with the wind to shake loose the seeds and spread them in the garden. Sometimes too much emphasis on seed production leads to a shorter lifespan of the plant.
Plant nurseries have long offered pentsemon seeds for sale. Starting in 1813, John Fraser sold four species of penstemon seeds in London. Over time, many hybrids were developed in Europe as new species were being discovered during western expeditions in the US. Today, a number of hybrids, cultivars and native plants can be found in seed catalogs and garden centers. I even have some plants that came from seeds collected in the wild and one or two that were transplanted from dirt roadways where their life expectancy did not look good.
For the enthusiast or any who just want more information, try the American Penstemon Society, an organization “dedicated to all things penstemon.” They promote the appreciation of these plants in both the garden and wild setting, while providing educational materials about growing them. You can also visit Plants of the Southwest, a source that I use for selecting penstemons that will grow in my zone.