The Acanthaceae or acanthus family is fairly large with some 2500-3000 species in about 250 genera. The family is known from a variety of very diverse tropical and subtropical habitats, and its four main centers of distribution are Indo-Malaysia, Africa, Brazil and Central America. It is composed of mainly annual and perennial herbs, shrubs and climbers, but also includes some large trees. The leaves are simple, opposite, estipulate and usually entire-margined, and the flowers are in spikes, racemes or cymes. Large and showy involucral bracts are fairly characteristic with tubular corollas that are 2-lipped or 5-lobed. The fruits are dehiscent capsules. Some of  the  familiar  genera in addition to Acanthus are Justicia, Thunbergia, Ruspolia, Barleria and Ruellia. Many species are popular ornamentals and others like zebra plant and nerve plant are commonly grown as house plants.