1289 Penstemon digitalisCommon Names: foxglove beardtongue,talus slope beardtongue,Mississippi penstemon,smooth white penstemon Family: Plantaginaceae (plantain Family)
Foxglove beardtongue is a vigorous perennial with a basal rosette of petiolate (= having leaf stems), glabrous (= hairless), subcoriaceous (= somewhat papery) leaves that are obovate (= spoon shaped). Leaf margins may be entire (= without teeth) or sparsely toothed. The basal leaves, 2-6 in (5-15 cm) long, are semi-evergreen, often persisting through the winter. One or two upright unbranched stalks, 2-5 ft (60-150 cm) tall, emanate from the basal rosette. The stalks are nearly hairless and may be tinged with purple. The cauline (= stem) leaves are lanceolate (= broadest below the center and tapering to a narrow tip), sessile (= without petioles) and opposite (= in pairs on the same plane, but on opposing sides of the stem). The inflorescence (totality of flowers on a single axis) atop the stalk is a panicle (= cluster of flowers on branched stems that radiate from a central unbranched axis). The corolla (= all the petals of an individual flower) is tubular (= petals are fused) , expanding abruptly like a bell with two lips; the upper lip with two lobes and the lower with three. The flower is about 1 in (2.5 cm) long, and white with pink or purple lines on the inside. There are four stamens (= the male, pollen bearing parts of the flower) and one pubescent (= hairy) staminode (= a modified stamen that lacks pollen). The flowers have no scent, but the vegetative parts (= stems and leaves) have a mildly fetid odor. The roots produce short rhizomes which may give rise to new plantlets around the base of the plant.
Foxglove beardtongue can be distinguished from the other beardtongues by the absence of hairs on the inflorescence (except for the staminode, of course), and the predominately white corolla.
A few selections have been named. “Husker Red’ has maroon leaves. ‘Albus’ has snow white flowers and ‘Nanus’ is a short, dwarf form.
Penstemon digitalis occurs in the eastern US, from the Great Plains to the Atlantic Coast, exclusive of Florida. This robust perennial grows in old fields, open woodlands, along roads and railroad tracks, and in waste places. It likes dry places, but sometimes grows where the drainage is poor. Some authorities believe foxglove beardtongue was originally restricted to the Mississippi Valley and has only in the last couple hundred years dispersed into its present range by colonizing along roads, railroads, farms and fields.
Light: Grow beardtongue in full sun, although it does okay in partial shade, and is grateful for partial shade in hot climates. Moisture: Foxglove beardtongue likes a moist soil. It does well in clayey soils or where the drainage is poor and tolerates seasonal flooding. (Note that most other beardtongues prefer dry and very well drained soils.) Foxglove beardtongue thrives in slightly acidic soils and does okay in calcareous situations. Hardiness: USDA Zones 3 - 8 . : Foxglove beardtongue blooms for a longer period in late spring and early summer than many spring bloomers. It takes the summer heat well. Propagation: Rhizomes can be divided in early spring. Seeds can be collected by shaking the dried, brown flower stalks after flowering and should be sown in late winter or spring. Some people have had success with cuttings taken in spring.
Foxglove beardtongue is an easy perennial for the casual garden. The flowers are tall and showy, and the basal leaves are big enough to compete with most weeds. It doesn’t mind wet feet once in a while and would be a good flower for a rain garden. The blooming period, around a month, is longer than many other spring bloomers. Use this big, vigorous perennial in the back of borders and beds, or massed in sunny openings. Turn it loose in a native plant garden.
There are more than 250 species on Penstemon, most native to western North America, with a just handful in eastern North America and a single species in Japan. Beardtongues as garden flowers became more popular in Europe before they were widely appreciated in the US. The Europeans produced hundreds of hybrids and cultivars derived from the western North American species.
The purple lines on the inside of the corolla are guidelines that direct bees to the nectaries within the flower. Passing through, the bees brush against the stamens, dislodging pollen that eventually gets smeared on the pistil (= female part of the flower). It’s a win-win symbiosis where the flowers get pollinated and the bees get nectar.
Steve Christman 6/20/17