Puprle beardtongue

Penstemons are in the Plantain (Plantaginaceae) family. The word “penstemon” is derived from the Greek words ‘pente” meaning five and ‘stemon’ meaning stamen. Of course this refers to the 5 stamens of Penstemon flowers.

The common name of Showy beardtongue is absolutely fitting, but I prefer Purple beardtongue or Purple Ozark beardtongue. As is often the case, there are numerous other common names:

• Cobaea beard-tongue
• Cobaea penstemon beard-tongue
• Prairie penstemon
• Purple penstemon
• Purple Ozark beardtongue
• Foxglove beardtongue
• Foxglove penstemon
• Large-flowered beardtongue
• Wild foxglove

On Ozarkedge, Purple beardtongue begins flowering in late April and extends through May. Sporadic flowering may be seen in June and July.

The large, tubular flowers are typically deep purple. But as you can see from the photos below, Purple beardtongue displays a range of shades from dark purple to a reddish purple and even a very pale purple. Some of the most striking flowers have the variation of a paler color on the face with the rest of the flower being dark purple.

Penstemon cobaea is a short-lived perennial that reseeds readily in a satisfactory habitat. It's basal rosette is easy to recognize in spring with its glossy, toothed leaves. This is a good time to transplant young plants.

The stem leaves of Penstemon cobaea are opposite and sessile. They have serrated edges and a beautiful waxy sheen.

The stem, buds, calyces and flowers are densely pubescent.

The filaments of the 4 stamen are almost like ribs, supporting the open flower and creating an inviting space for bees to crawl inside. The dark anthers holding the pollen can be seen dangling at the end of the filaments. The whitish style is centered in front of the stamens. A fifth sterile stamen (staminolde) protrudes from the mouth of the flower like a small brush.

The plant stands tall at a little more than 2 feet. Multiple stems with many flowers can be seen on a single plant. Occasionally, stems heavy with flowers will lean on other plants or flop to the ground, especially after a storm. They still put on a beautiful show and if left alone, the flowers will grow upright. I haven’t ever felt the need to stake them in the garden.

Large bees such as Bumblebees are the primary pollinators of Penstemon cobaea. Other visitors include hummingbirds, metallic green sweat bees, large carpenter bees, moths and other interesting insects.

It's fascinating to watch Bumblebees crawl deep inside the corolla until nothing is visible but their hind legs! As they maneuver into the flower, they pass by the stigma, inadvertently depositing pollen grains from visits to previous flowers, hence pollinating this flower. To reach their target, the nectary, they wiggle deep inside the flower, passing over the pollen covered stamens. When they back out of the flower, new pollen grains are dusted over their hair once more, ready to pollinate the next flower.

The video below shows an American Bumblebee (Bombus pensylvanicus) climbing inside one flower, backing out and flying into another.

This video shows a Brown-belted Bumblebee (Bombus griseocollis) visiting the flowers. This bee is not quite as large as the American Bumblebee, but its still an effective pollinator of Penstemon cobaea. I've also observed Two-spotted Bumblebees (Bombus bimaculatus) and Common Eastern Bumblebees (Bombus impatiens) pollinating the flowers by crawling into them.

Large carpenter bees (Xylocopa virginica) have a different method to get to the nectar. They obtain nectar by piercing the corolla at its base rather than climbing inside. In doing this, they bypass the pollen covered anthers and don't pollinate the flower.

Penstemon cobaea is most comfortable growing in rocky, limestone or dolomite glades and other open sunny, rocky areas. It is one of the most beautiful native plants to add to a sunny spot in a wildflower garden. It can be readily started from seed and, in the right conditions, will bloom the second year. It's also available at native plant nurseries.

Below are a couple of photos taken of Penstemon cobaea flowering in one of its native habitats, limestone glades.

Penstemon cobaea is native to 11 states. Natureserve lists it as Critically Imperiled in 2 states- Colorada and Iowa. It's listed as Vulnerable in Arkansas and Nebraska, and Apparently Secure in Oklahoma. All other states show no status on Natureserve.

Like many native wildflowers, Penstemon Cobaea plays an important role supporting many insects. While it is mostly pollinated by large bumblebees, it is also visited by smaller bees, butterflies, moths and other interesting insects as well as hummingbirds. It is a host plant for the Dotted Checkerspot butterfly.