VERBENA

genus of plants in the family Verbenaceae that contains several species of garden flowers. Verbena consists of about 250 species, almost all of them native to the tropical and subtropical Americas, including 20 in the United States. Two species are indigenous to the Old World. Most verbenas are perennials, though a few are annuals. They usually have opposite leaves that are toothed, lobed, or dissected. The flowers are small to medium-sized and are usually borne on spikes. The best-known species is the common garden verbena (V. hortensis, or hybrida), which is derived from various South American species. This square-stemmed, creeping plant bears flat heads of phloxlike flowers that sometimes have yellow eyes. Its flowers range in colour from pure white to pink, red, blue, violet, and yellow and also occur in striped varieties. Forms of the North American clump verbena (V. canadensis) are also sometimes cultivated as garden flowers. Most other species in the United States are low-growing, small-flowered, somewhat weedy plants that are referred to as vervains rather than verbenas. The blue vervain (V. hastata) reaches a height of 1.5 m (5 feet) and produces spikes of blue to purple flowers. The Eurasian species V. officinalis was once considered a medicinal plant.