Beard tongue is drought and clay tolerant, good for restoration projects. Photo credit: Robert H. Mohlenbrock @ USDA-NRCS PLANTS Database / USDA SCS. 1989. Midwest wetland flora: Field office illustrated guide to plant species. Midwest National Technical Center, Lincoln.
FIRST IMPRESSIONS: Penstemon digitalis is an elegant perennial wildflower that expands to form upright clumps. This beardtongue bears deep green leaves on strong upright stems. In summer, plants are topped by showy panicles of tubular snapdragon-like white flowers. Pollinators flock to the blooms in sunny or partly shaded sites with well drained loamy soil.
HABITAT & HARDINESS: Penstemon digitalis occurs in the eastern United States from Maine to Georgia and west to South Dakota and Texas.
This species is indigenous to dry or mesic Blackland prairies, savannas, edges and clearings of floodplain or upland forests, acid gravely seeps, thickets, pastures, disturbed fields and right of ways. Plants occur in high quality and disturbed habitats and in wetlands or well drained sites.
Plants are hardy from USDA Zones 3-8.
PLANT DESCRIPTION: Penstemon digitalis is an upright rhizomatous perennial with clustered red-purple rosettes and smooth green stems.
Leaves are glossy with occasional reddish highlights. They are opposite with pointed tips and ovate, elliptical or lanceolate shape. Blades are up to 6” long and 2-3” across with smooth edges or tiny teeth on the margin.
The stems terminate in showy branched flower panicles. The florets are tubular, lobed and about 1” long. The outer surface of the corolla tube is white or pale pink and the inner surface is often marked with violet nectar guides.
Plants bloom for about a month in late spring or early summer. Small capsules full of tiny seed follow persisting into early winter.
Plants grow 2-4’ tall with 1-2’ spread.
CULTURAL & MAINTENANCE NEEDS: Penstemon digitalis flourishes in sunny sites with wet or moist acid loamy soil. Plants tolerate clay loam, sand, alkaline pH, heat, drought, part sun and dry shade.
Deadheading to remove dried stalks in fall will allow the lovely purplish rosettes to function as a winter groundcover.
Plants are pest resistant and unpalatable to deer and other herbivores.
LANDSCAPE USES: This is a good choice for a Wildlife Garden, Cut Flower Garden, or Meadow. Plants are also used as Butterfly Nectar Plants or as part of a Grouping or Mass Planting. In mild climates attractive rosettes provide Winter Interest. Penstemon digitalis has Showy Blooms and is appropriate for Cottage Gardens, Deer Resistant Plantings, Water-wise Landscapes, Low Maintenance Plantings, Rain Gardens and Perennial Borders.
COMPANION & UNDERSTUDY PLANTS: Try pairing Penstemon digitalis with Baptisia australis, Ceanothus americanus, Liatris aspera, Monarda fistulosa or Sorghastrum nutans.
Penstemon calycosus has similar appearance and culture and could be substituted in some situations.
TRIVIA: Long tongued bees, butterflies, sphinx moths and hummingbirds sip nectar from the flowers. Caterpillars of several moth species feed on the foliage.
Penstemon digitalis can be differentiated from P. calycosus because it is taller with white flowers and shorter sepals. It is less shade tolerant than P. calycosus and more likely to be found in dry sunny plant communities.
Penstemon is derived from Greek and means five stamens. The specific epithet is from a Latin word meaning finger because the flower buds look like finger tips.
The common name “beardtongue” was adopted because the flowers contain a sterile stamen with a pubescent or “bearded” stalk. Penstemon digitalis is commonly called Mississippi Penstemon because it is thought to have once been indigenous only to habitats in the Mississippi River Basin.
For more information on this plant, visit the USDA PLANTS Database: http://plants.usda.gov/java/profile?symbol=PEDI