Blue vervain is a tall, slender, erect perennial with branching, 4-angled stems and rough hairs. Flowers in many terminal spikes, deep purple, violet, light lavender, rarely white. Flowers tubular, 5-lobed, opening from the base of spike upward. Blooms June-October. Leaves opposite, on short but distinct petioles, quite variable, lance-shaped to ovate, some with 2 lobes near the base (halberd-shaped), rough-hairy, coarsely double-toothed, to 5 inches long.
Similar species: Missouri has 7 Verbena species, 5 with a wide distribution. Creeping vervain (V. bracteata) is a low, spreading plant bearing short spikes of flowers. The others are upright plants: Hoary vervain (V. stricta) has stalkless, broadly ovate leaves and is densely hairy. White or nettle-leaved vervain (V. urticifolia) has broadly ovate leaves that are noticeably stalked on the main stem; its flowers are very small and white. Narrow-leaved vervain (V. simplex) has narrowly lanceolate leaves.
Height: to 5 feet.
Most common north of the Missouri River and in our central and western counties. Scattered in the Ozarks.
Habitat and Conservation
Occurs in low, wet places, streamsides, sloughs, lakes, wet prairies, pastures, and woodlands; also wet ledges of bluffs, railroads, roadsides, and waste places.
Used as a native garden plant. Various parts of this plant were used by Native Americans and settlers to treat maladies ranging from seizures to nosebleeds and respiratory ailments. In the 1700s American doctors were using it as an emetic. Settlers used it as a "spring tonic."
Butterflies are attracted to blue vervain (which endears it to gardeners), as are numerous other nectar-loving insects. Juncos and some species of sparrows are known to eat the seeds.