Blue vervain (Verbena hastata) is a creeping perennial growing to 5 ft by 2 ft. It is in flower from July to August. The flowers are hermaphrodite (have both male and female organs) and are pollinated by bees, flies, lepidoptera, self. The plant is self-fertile. The blue vervain or verbena is a plant of the mint family, bearing numerous, small lilac-blue flowers.