South Dakota Native Plant Research
Scrophulariaceae: Penstemon gracilis

Scrophulariaceae: Penstemon gracilis


Download Seed: The seeds of slender beardtongue are brown and very tiny, 0.6-0.8 mm long. (58 KB)

Download Seedling: One month old seedling grown in research greenhouse at SDSU. (668 KB)

Download Vegetative: The 3-9 cm long leaves are entire to sharply toothed. (70 KB)

Download Flowering: Slender beardtongue flowers in a narrow panicle. (1007 KB)

Download Fruiting: The seeds are located inside capsules. (521 KB)

Download Research garden: First seasons growth in research garden near SDSU. (96 KB)

Download Research garden: Second year plants (1.0 MB)

Family Name


Common Name

Slender beardtongue, Lilac Penstemon

Native American Name

Lakota: zuzéča tȟapȟéžuta


Penstemon gracilis is a perennial herb with 1-several erect stems growing from a woody caudex, generally 20-50 cm tall and often reddish colored with glandular hairs toward the top. The simple basal leaves have a short, winged petiole, the lanceolate to ovate blade 2.5-7.5 cm long and 4-15 mm wide, with a few to many teeth. The linear to lanceolate cauline leaves are opposite, clasping the stem, 2.5=9 cm long and 2-15 mm wide, with similarly toothed margins. The leaves are smooth to sparsely hairy. The inflorescence is a panicle, 5-21 cm long, of 2-6 flowered axillary cymes. The 5 calyx lobes are 4-6 mm long and up to 2 mm wide, with glandular hairs. The corolla is bilabiate, 15-22 mm long, pale lavender to pink externally and lighter colored within. The slender corolla tube has glandular hairs, the throat is 4-6 mm wide, with darker lines inside and a beard of whitish hairs going back about halfway. The upper lip is reflexed, and the lower lip extended. The 4 black-tipped stamens hug the upper surface, and a sterile lower stamen forms a beard of yellow hairs. The fruit is a 6-8 mm long capsule. Slender beardtongue blooms from May to August on sandy or gravelly soil in prairies, valleys, and at lower elevations in mountains throughout much of South Dakota.

Additional Notes

Slender beardtongue is a bright and eye catching addition to a native plant garden. The flowers are attractive and bloom for an extended period, especially if deadheaded. The flowers provide nectar and pollen for bees, butterflies, and other insects. The plants are also quite drought tolerant.

Horticulture Notes

Seed Collection: Collect seed in June-August when capsules and seeds have turned brown.

Germination: Plant seeds outdoors in late fall into early spring. They need a 60 day cold-moist treatment to germinate.

Soils: Sandy or gravelly, well drained

Light: Full sun to partial shade.

Water: Moderate to dry conditions.

Scrophulariaceae: Penstemon gracilis