Taxonomy and distribution of species of the genus acanthus (Acanthaceae) in mangroves of the Andaman and Nicobar Islands, India

Abstract

A recent floristic survey revealed the occurrence of three species of Acanthus in mangroves of the Andaman and Nicobar Islands, India. Of these Acanthus ilicifolius and A. ebracteatus are shrubs, whereas A. volubilis is a climbing shrub. All the three Acanthus species were recorded from the Andaman Islands, but only A. ilicifolius from the Nicobar Islands. A. volubilis is easily distinguished from other two species by its unarmed and twining with delicate sprawling stems, un-serrated elliptical leaves, white corolla and absence of bracteoles. A. ilicifolius and A. ebracteatus are differentiated based on the presence and absences of bracteoles, corolla color, and position of Inflorescence and direction of stem axial spines. A key for the species of Acanthus of the Andaman and Nicobar Islands is also provided.