Blue vervain, also known as simpler's joy or wild hyssop, is a flowering perennial plant native to the United States and parts of Canada. The plant's Latin name is Verbena hastata, which means “sacred herb” and “halberd-shaped,” referring to the shape of the basal leaves. The herb is a member of the family Verbenaceae, also known as the Verbena family, which contains numerous aromatic herbs that produce spikes or clusters of flowers.
Blue vervain is commonly found growing in small colonies in meadows, fields, marshes, drainage ditches and along streams or creeks. Each plant can reach up to 4 feet (1.2 meters) in height, and produces long, stalked leaves that are rough to the touch and tapered toward the tip. The square stem branches out above the foliage and bears 12 or more flower stalks per plant in summer through fall.
The blue, tubular flowers are about 1/8 inch (3 millimeters) wide with five small lobes. Blue vervain flowers are insect-pollinated and rich in nectar. They attract honeybees and bumblebees, which are the plant's primary pollinators. The flowers die back in late fall, but the stalk often remains throughout winter to disperse seed. In late summer, small red buds appear just below the soil's surface, and new stalks grow from the buds the following year.
Native Americans used blue vervain for a variety of culinary and medicinal purposes. The seeds were harvested and ground into flour for cooking or eaten raw, and the leaves were made into tea. Medicinally, the herb was used as an emetic, or substance that induces vomiting, for treating fevers and stomach problems.
The bruised leaves of the blue vervain plant are used in folk medicine for treating headaches, earaches and rheumatism. When placed externally on the affected area, the juice from the leaves is believed to provide relief from pain. Tea made from the leaves is traditionally used to treat piles and idney or bladder stones.
Although humans have used blue vervain for centuries, it is also an important plant for a variety of animals and insects. The verbena moth feeds on the herb's leaves in spring, swamp sparrows and cardinals eat the seeds, and cottontail rabbits eat the leaves and stems. Some insects that feed on blue vervain are parasites that may kill the plant if not controlled. These include the verbena leaf miner and parasitic dodder, both of which sap the plant's nutrients.