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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 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.

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Studies on phenology, floral biology and seed production were conducted in two provenance trials and a clonal hedge orchard of C. equisetifolia. Observations in seventeen populations indicate that predominant dioecy with low proportion of monoecy as the commonest sexual strategy. Flowering occurs twice in a year coinciding with the South West and North East monsoons. C. equisetifolia exhibits strong anemophilous adaptations such as very high pollen output, reduced flowers with large stigmatic area and light weighing winged fruits. Pollen is viable up to 99%, storable in 4°C up to three months with no loss in fertility. Trees start reproducing within two years of planting. Local land races produce ten to twenty times higher seeds than the recent introduced natural provenances and exotic landraces. Controlled pollination resulted in lower seed set than observed in open pollination. Selfing leads to normal seed set in monoecious trees. Inter specific cross with C. junguhuhniana pollen parent results in viable progeny.