Acanthus is a genus of about 30 species of flowering plants in the family Acanthaceae, native to tropical and warm temperate regions, with the highest species diversity in the Mediterranean Basin and Asia. This flowering plant is nectar producing and is susceptible to predation by butterflies, such as Anartia fatima, and other nectar feeding organisms. Common names include Acanthus and bear's breeches. The generic name derives from the Greek term ἄκανθος (akanthos) for Acanthus mollis, a plant that was commonly imitated in Corinthian capitals.

Acanthaceae is a family of dicotyledonous flowering plants containing almost 250 genera and about 2500 species. Most are tropical herbs, shrubs, or twining vines; some are epiphytes. Only a few species are distributed in temperate regions. The four main centres of distribution are Indonesia and Malaysia, Africa, Brazil, and Central America. Representatives of the family can be found in nearly every habitat, including dense or open forests, scrublands, wet fields and valleys, sea coast and marine areas, swamps, and mangrove forests.