The Button Mangrove Conocarpus erectus (Combretaceae) is naturalised in Western Australia

Abstract

Conocarpus L. (Combretaceae) comprises two species of tall shrubs to small trees. Conocarpus lancifolius Engel. is native to and restricted to seasonal rivers and coastal sites around the Red Sea from Somalia to Yemen, and coastal riverine sites in southern Asia (Thulin 1993). Conocarpus erectus L. is native to coastal sites in southern Florida, Bermuda, the Bahamas, the West Indies and Mexico, as well as the Atlantic coast of Brazil, the Pacific coast from Mexico to Peru including the Galapagos Islands, and the west coast of Africa from Senegal to the Democratic Republic of the Congo (Barwick 2004). Both species are widely planted throughout the Middle East, Africa and south-west Asia. Conocarpus erectus (Button Mangrove or Button Wood) is a dense, multi-trunked shrub or tree to 20 m high that normally grows in brackish water and tidal lagoons but is sometimes found in inland riverine areas in Central America. It has two currently recognised named forms, the Green Buttonwood (var. erectus), which has hairless to sparsely hairy leaves, and the Silver Buttonwood (var. sericeus Fors ex DC.), which has densely hairy, silver leaves. Both have been widely cultivated as medicinal, ornamental and reclamation plants, especially in India and the Middle East (Barwick 2004). In its native habitat, C. erectus appears to occupy the zone between the mangrove species inundated by salt water and the dry land behind. In cultivation, it thrives on dry soils (away from indigenous mangroves), calcareous clays with a high, brackish water table, and poor sandy soils. Established plants are very drought tolerant and can form extensive thickets by sprawling and rooting where stems touch the ground; even large stems broken by cyclones and floods are capable of rooting on damp ground (Barwick 2004). Plants bear wind pollinated flowers that can produce a large number of small seeds (7,441-23,267 seeds/m2) that are wind and water dispersed, with plants flowering and fruiting throughout the year (Hernandez & Lanza Espino 1999).