Scrophulariaceae : Penstemon grandiflorus

Penstemon grandiflorus is a weakly perennial herb with 1-3 erect, smooth, waxy stems arising from a woody caudex growing up to about 1 m tall. The blue-green leaves are both basal and cauline, thick (succulent) and often covered in a waxy bloom, with entire margins. The basal and lower most stem leaves are shortly petiolate, spatula-shaped to orbicular, 3 to 16 cm long, 1-5 cm wide, rounded to pointed at the tip and tapering at the base. The sessile, opposite, ascending cauline leaves are 2- 9 cm long, 1.5-5 cm wide, more broadly egg-shaped, clasping at the base and reduced to bracts on the upper stem. The inflorescence consists of 3-9 clusters of flowers, with peduncles arising in the axils of the upper leaves, each cluster having 2-4 flowers on short pedicels. The green calyx has 5 lobes, 7-11 mm long. The bilabiate corolla is 35-48 mm long, abruptly inflated, lavender to bluish purple in color, the throat 15-18 mm wide, with magenta nectar guides on the inside. The lobes of the upper lip are spreading to reflexed, the lower lips spreading. The style and 4 stamens with black anthers hug the upper part of the tube and a white sterile stamen with a few yellow hairs on its tip is contained within the tube. The fruit is an ovoid capsule, 16-25 mm long containing several black to brown seeds up to 4 mm long. Large-flowered beardtongue blooms in May and June on prairies scattered throughout South Dakota.