Species Native to Missouri
Common Name: dew flower
Type: Herbaceous perennial
Family: Plantaginaceae
Native Range: Central United States
Zone: 5 to 8
Height: 1.00 to 3.00 feet
Spread: 1.00 to 1.50 feet
Bloom Time: May
Bloom Description: Purple
Sun: Full sun
Water: Dry to medium
Maintenance: Low
Flower: Showy
Tolerate: Deer, Drought, Dry Soil, Shallow-Rocky Soil
Culture
Easily grown in average, dry to medium, well-drained soils in full sun. Prefers somewhat dry, calcareous soils. Avoid wet, poorly-drained soils.
Noteworthy Characteristics
Penstemon cobaea is a clump-forming, Missouri native perennial which occurs on prairies, limestone glades and rocky bluffs. Typically grows 1-2.5' tall. Features loose, terminal panicles of white to violet to deep purple, 2" long, tubular flowers atop erect, rigid, downy stems. Flowers bloom in mid-spring and are somewhat larger than most penstemons. Downy, clasping, lance-shaped upper leaves.
Var. purpureus has uniformly purple flowers whereas the species, Penstemon cobaea, has white to pale lilac flowers. Var. purpureus is an uncommon, clump-forming, Missouri-native perennial which occurs only on certain limestone glades in the area of the White River and its tributaries in the southern Missouri Ozarks. Typically grows 1-2.5' tall. Features loose, terminal panicles of violet-purple to rose-purple tubular flowers (to 2" long) atop erect, rigid, downy stems. Flowers bloom in mid-spring and are somewhat larger than many of the other species of penstemon.
Genus name comes from the Greek words penta meaning five and stemon meaning stamen in reference to each flower having five stamens (four are fertile and one is sterile).
Penstemons are sometimes commonly called beard tongues because the sterile stamen has a tuft of small hairs.
Problems
No serious insect or disease problems. Root rot can occur in wet, poorly-drained soils.
Uses
A rare plant for limestone rock gardens, native plant gardens or borders.