Description: This is a slender, but erect, native perennial plant that is up to 5' tall, branching occasionally in the upper half. The green or red stems are four-angled, sometimes with fine white hairs. The opposite leaves are up to 6" long and 1" across. They are lanceolate, conspicuously veined, and have short petioles. The margins are coarsely serrated with variably sized teeth. The upper stems terminate in a panicle of flowering spikes. These erect spikes are up to 5" long, and densely crowded all around with numerous reddish blue or violet flowers. Each flower is a little less than ¼" across, and has 5 lobes flaring outward from a slender corolla tube. There is no scent. Four nutlets are produced per flower they are reddish brown, oblong, and triangular convex. The blooming period occurs from mid- to late summer, and lasts about 1½ months. The root system has fibrous roots and short rhizomes.
Cultivation: The preference is full sunlight and moist conditions. The soil should consist of a fertile loam or wet muck. This plant tolerates standing water, if it is temporary. This is a good plant to locate near a small river or pond in a sunny location.
Range & Habitat: Blue Vervain occurs in every county of Illinois. It is fairly common, and can be found in moist black soil prairies, particularly in disturbed areas. This plant also occurs in moist meadows near woodland areas, in thickets and pastures, along fence rows, and along ditches, rivers, or ponds in sunny areas.
Faunal Associations: The flowers attract many kinds of long-tongued and short-tongued bees, including Epeoline Cuckoo bees, Eucerine Miner bees, Halictid bees, and the oligolege Calliopsis verbenae (Verbena Bee). These bees seek primarily nectar, although some species collect pollen. Other flower visitors include Ammophila spp. (Thread-Waisted wasps), Bee flies, Thick-Headed flies, small butterflies and skippers, and Chauliognathus pennsylvanicus (Goldenrod Soldier Beetle). The caterpillars of Crambodes talidiformis (Verbena Moth) feed on the foliage. Most mammalian herbivores avoid eating this plant because of the bitter leaves an exception is the Cottontail Rabbit, which may eat the foliage of young plants to a limited extent. Also, various songbirds occasionally eat the seeds, including the Cardinal, Swamp Sparrow, Field Sparrow, Song Sparrow, and Slate-Colored Junco (during the winter). Experimental studies have shown that these seeds can pass undamaged through the digestive tracts of cattle, therefore they are probably distributed to some extent by these seed-eating birds.
Comments: The flowers are often a pretty blue or violet, but they are quite small. Blue Vervain is easy to identify because it is the only vervain with elegant spikes of flowers in this color range.