This section is from the book "Handbook Of Hardy Trees, Shrubs, And Herbaceous Plants", by W. Botting Hemsley. Also available from Amazon: Handbook of hardy trees, shrubs, and herbaceous plants.
Annual or perennial herbs or undershrubs with opposite or whorled simple pinnatifid or lobed leaves. Calyx ribbed, irregularly 5-toothed. Corolla salver-s h a p e d; tube often curved; limb regular, spreading, or more or less bilabiate. Stamens 4, included. Fruit splitting into four 1-seeded nutlets. The species are estimated at about 70, nearly all of which are American. We have, however, one common European species which extends to England, and is especially abundant in the south. It is the V. officinalis, Vervain, a slender plant from 1 to 3 feet high with opposite oblong pinnatifid or tripartite leaves and elongating bracteolate dense spikes of small lilac flowers. The generic name is of classical origin, but the signification is obscure.
Fig. 197. Verbena Aubletia. (1/4 nat. size.)
1. V. Aubletia (fig. 197). - This handsome plant appears to have been the first species introduced of those which have contributed to the brilliant array of hybrids now in cultivation. A hairy plant having deeply-cut trilobate leaves and rosy-purple flowers. It is a native of North America and of annual duration, introduced in 1774. V. Drummondii is a variety of this.
2. V. chamcedrifolia, syn. V. Melindres and V. melissoldes. - A South American perennial species of creeping habit with regularly toothed not laciniate leaves and umbellate reddish violet flowers in the variety first introduced. 1827 is the date recorded of its introduction. V. teucrioides, from the same country, is probably a natural variety of this species with white or rose-coloured fragrant flowers.
This species is believed to be the principal parent of the garden varieties, though the typical plant is lost in the maze of hybrids. It is, however, probable that several species or natural varieties are variously blended and intermixed in the garden forms. V. incisa is a very beautiful allied plant from South America with ovate-lanceolate irregularly toothed petio-late leaves and long-stalked umbels of pale red flowers. Some of the hybrid varieties in cultivation are perhaps due to crosses between V. incisa and V. chamaedrifolia.
3. V. pulchella, syn. V. tenera. - A distinct perennial species of creeping habit with square stems.and deeply-cut leaves, and smaller heads of smaller flowers. The divisions of the leaves are narrow and distant, and the flowers usually variegated in two or three colours. The variety Mahonetti with striped flowers belongs here. It is a native of South America, and was introduced in 1827.
It is almost superfluous to allude to the numerous varieties further than to remark that they exhibit every shade and tint of lilac, purple, pink, scarlet, and crimson, and also pure white. They are for the greater part uniformly coloured, but there are some handsome striped and bordered varieties.
V. venosa is a hardy herbaceous species from South America of erect habit, with sessile entire somewhat rugose leaves and elongating heads of violet or bluish violet flowers. V. alata has a branched inflorescence, and is remarkable for its deeply 4-winged stems.
The genus Lantana consists chiefly of South American shrubs and herbs having opposite simple leaves and axillary pedunculate heads of small variously-coloured flowers. The fruit is 2-celled and drupoid. For bedding purposes some of the perennial species are treated as annuals. L. Gamara is the variable species commonly seen, with changeable flowers, yellow, white, orange, red, lilac, and intermediate tints, arranged in dense hemispherical heads.