(Verbenaceae). Genus of about 250 species of summer and autumn flowering tuberous or rhizomatous herbaceous perennials, some of which are semi-evergreen. Occurs in usually open and sunny habitats such as prairies, wasteland and roadsides and in open woodland (some species prefer dry sites, others moist). Almost all are from tropical and temperate regions of North, Central and South America; a few are from S. Europe. The erect or procumbent square stems are usually opposite, toothed, sometimes lobed to pinnatifid leaves. They bear small flowers in dense, terminal spikes, panicles, cymes or corymbs, occasionally singly. The flowers, often brightly coloured are salverform each with a tubular corolla spreading at the mouth. Some are tall and airy, others ground hugging and are long flowering. Good in containers, borders, edging and baskets.