Hoary Vervain is a vigorous, clump-forming, short-lived plant growing from a root system with a central taproot.  It is a square-stemmed perennial covered with white hairs, giving the plant a grayish cast. Their oblong leaves are also covered with hairs; hence the name, "hoary".  They have multiple upright flower stalks packed with small blue-purple tubular flowers.  This plant thrives in full sun and dry to medium well-drained soils.  It also adapted for good drought resistance.  Found in sandy fields, dry prairies, mesic prairies, and roadsides, their flowers are visited by bees, butterflies, and wasps.  Their seeds are also eaten by birds.  Hoary Vervain is not generally consumed by animals like deer or rabbits since the foliage is bitter.  Leaves were used by Native Americans for medicine.  Other common names are woolly verbena, hairy blue vervain, hoary verbena, and mullein-leaved verbena.