Foxglove Beardtongue

Penstemon digitalis

foxglove_or_smooth_beardtongue.jpg

Photo of foxglove beardtongue flowers
The flowers of foxglove beardtongue are white, tubular, with 2 lobes above and 3 below. They are arranged in clusters on a stout stalk that can grow to 4 feet tall.
David Stonner
Other Common Name
Smooth Beard-Tongue; Foxglove Penstemon; Tall White Beard-Tongue
Family

Plantaginaceae (plantains); formerly Scrophulariaceae (figworts)

Description

Foxglove, or smooth beardtongue is a  clump-forming, perennial herb; it is the tallest of the 4 white-flowered penstemons in Missouri. Flowers in loose terminal clusters; each flower 1¼ inches long, irregular, with 2 lips: the upper 2-lobed, the lower 3-lobed. Of the 5 stamens, 1 is modified into a hairy “tongue” and positioned centrally, probably to attract insects for pollination (hence the name "beard tongue"). Blooms May–July. Stem leaves opposite, lance-shaped, sessile (stalkless), with small, widely spaced teeth.

Size

Height: to 4 feet, but usually shorter.

Habitat and conservation

Occurs in rich or low moist woodlands and woodland borders, thickets, prairies, old fields, rights-of-way.

iamge of Smooth Beard-Tongue Tall White Beard-Tongue Foxglove Beardtongue distribution map
Distribution in Missouri

Statewide, except extreme northwestern counties.

Status

Penstemons used to be placed in the Scrophulariaceae, the figwort family. Recently, botanists have been using the new tool of molecular (DNA) research to study relationships among plant groups. They have determined that the former "scroph" family contained several groups of plants that truly belonged in other families, so they "disintegrated" the Scrophulariaceae. Penstemons are now placed in the now-much-larger Plantaginaceae, or plantain family.

Human connections

This is a popular native plant for landscaping, and cultivars are available that have (for example) burgundy foliage or different-colored flowers. This species is striking when massed in sunny borders. Penstemons are some of our continent's most attractive native flowers.

Ecosystem connections

This plant attracts bees, butterflies, moths, and hummingbirds. Apparently, few herbivores eat its foliage. The roots (along with those of all the other plants) help to stabilize the soil, even during seasons when this perennial plant is dormant.