Figwort family (Scrophulariaceae)
Description: This native perennial wildflower is 12½' tall and unbranched. The erect central stem is pale green, terete, and covered with short pubescence. The opposite leaves are up to 3" long and ¾" across; they are linear-lanceolate or lanceolate-oblong, pale green, and smooth to slightly dentate along their margins (if teeth are present, they are small and widely spaced). Both the lower and upper surfaces of the leaves are short-pubescent. The central stem terminates in a panicle of flowers that is taller than it is wide. Individual flowers are about ¾" long, consisting of a white tubular corolla and a short pale green calyx with 5 teeth. The corolla becomes gradually wider, forming an upper lip with 2 lobes and a lower lip with 3 lobes. The lower lip projects outward to a greater extent than the upper lip. Along the bottom of the corolla's interior, there are 3 faint purple veins and a pair of low ridges. Toward the throat of the corolla, there is an elongated patch of yellow hairs. The exterior of the corolla is slightly pubescent. The pedicels and calyces of the flowers are also pubescent. The blooming period occurs from mid-spring to early summer and lasts about 3 weeks. There is no noticeable floral scent. Each flower is replaced by a seed capsule containing several small seeds. This wildflower reproduces by reseeding itself.
Cultivation: Full to partial sun and mesic to dry conditions are preferred. Different kinds of soil are tolerated, including those containing clay-loam, sand, or rocky material. Reduced soil fertility is beneficial, because this reduces competition from taller and more aggressive plants.
Range & Habitat: Pale Penstemon is occasional throughout Illinois, except in east-central and some northern areas of the state, where it is uncommon or absent (see Distribution Map). Habitats include dry rocky woodlands, hill prairies, dry-mesic railroad prairies, sandstone and limestone glades, upland savannas, thinly wooded bluffs, rocky cliffs, and abandoned fields. Occasional wildfires are beneficial in maintaining populations of this species, particularly in wooded habitats.
Faunal Associations: Not much is known about floral-faunal relationships for this species, however insect visitors of its flowers are probably similar to those of Penstemon hirsutus (Hairy Penstemon). Such visitors would include bumblebees, Mason bees (Osmia spp.), Digger bees (Synhalonia spp.), and bee flies. Butterflies may also visit the flowers, but they are less effective at cross-pollination. The caterpillars of the moths Elaphria chalcedonia (Chalcedony Midget) and Pyrrhia exprimens (Purple-Lined Sallow) feed on Penstemon spp. (Penstemons); the caterpillars of the latter feed on the flowers, buds, and developing seed capsules. Generally, mammalian herbivores appear to avoid consumption of the foliage, and birds display little interest in the seeds.
Photographic Location: A small meadow at Busey Woods in Urbana, Illinois.
Comments: Pale Penstemon is a reasonably attractive wildflower that blooms a little earlier than other Penstemon spp. (Penstemons). It can be distinguished from these other species by its evenly pubescent foliage and the following characteristics of its corolla: 1) the lower interior surface is distinctively ridged, rather than flat or concave, 2) the lower lip extends significantly beyond the upper lip, 3) the exterior is white, rather than pale rose-purple. Overall, Pale Penstemon is more dainty in appearance than its taller and more aggressive cousin, Penstemon digitalis (Foxglove Penstemon). Another common name is Pale Beardtongue (or Beardstongue), which refers to the yellow hairs that line the throat of the corolla.