VERBENA. The genus Verbena (vervain) in botany gives its name to the family (Verbenaceae), of which it is a member. The species are herbaceous or somewhat shrubby, with opposite or whorled leaves, generally deeply cut. The sessile flowers are aggregated into close spikes. Each flower has a tubular, ribbed calyx, a more or less irregular tubular two-lipped corolla, with four (didynamous) stamens springing from the interior of the corolla-tube. The anthers are two-celled. The ovary is entire or four-lobed, and always four-celled, with a single ovule in each cell. The fruit consists of four hard nutlets within the persistent calyx. There are about ioo species, mostly natives of tropical and subtropical America, some 20 being native to the United States, a very few species occurring also in the Old World. The garden verbenas are mostly derivatives from a few South Ameri can species, such as V. teucrioides, of southern Brazil, and V.
chamaedrifolia from Argentina and southern Brazil. Various cultivated forms have been derived also from the North American V. canadensis. The range of colours extends from pure white to rose-coloured, carmine, violet and purple. Striped forms also are cultivated. The lemon-scented verbena of gardens, much valued for the fragrance of its leaves is now referred to the genus Lippia as L. citriodora; it differs from Verbena in having two, not four, nutlets in the fruit.
The garden verbenas are easily raised from seeds sown in heat in February or March, but choice varieties can only be kept true when raised from cuttings. These are best secured from old plants cut down in the autumn and started into growth in gentle heat and moisture the following spring. They root readily in a compost of sandy loam. (See VERBENACEAE; VERVAIN.)