ACANTHUS, a genus of plants of the acanthus family (Acanthaceae), embracing some 20 species, mainly perennial herbs and small shrubs, native to the Mediterranean region and the warmer parts of Asia and Africa. They are bold, vigorous, hand some plants, with mostly broad, much divided, often spiny-toothed leaves. The erect stems bear stately spikes of showy white, purple or red flowers, surrounded by sharp-pointed, sometimes highly coloured bracts. Several species are grown as ornamentals. These are mostly thistle-like plants, with stems 3 ft. to 4 ft. high, the best known of which is the bears' breech or brankursine (A. mollis), common in Mediterranean countries, with deeply cut, hairy, shining leaves, which are without spines, and whitish or rose-coloured flowers in spikes al ft. long. The spiny acanthus (A. spinosus), native to southern Europe, is so named because of its very spiny leaves. A. Parringi, a native of Asiatic Turkey, with red flowers, is suitable for rock gardens. A. montanus, native to Greece, with roseate flowers, is grown in greenhouses.
In architectural decoration, the acanthus was first reproduced in metal, and subsequently carved in stone by the Greeks. It was afterwards, with various changes, adopted in all succeeding styles of architecture as a basis of ornamental decoration. There are two types, that found in the Acanthus spinosus, which seems to have been followed by the Greeks, and that in the Acanthus mollis, which seems to have been preferred by the Romans.