Smooth Beard-Tongue (Tall White Beard-Tongue; Foxglove Beardtongue)

Family: 
Plantaginaceae (plantains); formerly Scrophulariaceae (figworts)
Description: 

A clump-forming, perennial herb; 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.
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.