The wetlands of the Amazon cover an area of ca.2 millions of Km2,corresponding to approximately 30% of the total basin area.In central Amazonia the prevailing floodplain forests are differentiated into nutrient-rich white water"várzea"and nutrient-poor black water or clear water"igapó".Igapó forests occur along rivers that drain the Paleozoic and/or Precambric Shields of Guyana and Central Brazil such as the Negro River,which form the largest black-water inundation forests in the world.However,despite its significant extension and ecological importance there is a lack of scientific floristic data on the igapó forests.