other species occur. In this area where there are variations in soil and topography and the rainforest experiences conditions of all-year-round humidity, the genus Hevea has been undergoing a high degree of speciation. The high humidity encourages the growth of fungal leaf diseases, and the species that are deciduous avoid immediate transfer of fungal spores from old leaves onto new growth. The Pará rubber tree has been introduced to and is naturalised in many tropical countries in Asia. Habitat Each species has its own habitat requirements; H. brasiliensis grows on well-drained soils but tolerates light flooding; H. guianensis, H. pauciflora and H. rigidifolia grow in well-drained soil, on high river banks and on slopes; and H. camporum grows on savannahs. Other species such as H. benthamiana, H. microphylla and H. spruceana need wetter conditions in locations subject to seasonal flooding for several months each year, and H. nitida grows both in periodically inundated swamps and in drier locations such as rocky hillsides well above the flood level. Species The following species are recognised: Hevea benthamiana Müll.Arg. – Venezuela, SE Colombia, N Brazil Hevea brasiliensis (Willd. ex A.Juss.) Müll.Arg. – Pará rubber tree – Brazil, French Guiana, Venezuela, Colombia, Peru, Bolivia; naturalized in parts of Asia and Africa and on some tropical islands Hevea camargoana Pires – Marajó, Pará State in Brazil Hevea camporum Ducke – Amazonas State in Brazil Hevea guianensis Aubl. – Venezuela, Ecuador, Peru, Guyana, Suriname, French Guiana, Colombia, N Brazil Hevea microphylla Ule – Venezuela, Colombia, N Brazil Hevea nitida Mart. ex Müll.Arg. – Colombia, Amazonas State in Brazil Hevea pauciflora (Spruce ex Benth.) Müll.Arg. – Venezuela, Peru, Guyana, Suriname, French Guiana, Colombia, N Brazil Hevea rigidifolia (Spruce ex Benth.) Müll.Arg. – Vaupés region of Colombia, Amazonas State in Brazil Hevea spruceana (Benth.) Müll.Arg. – Guyana, Amazonas State in Brazil References External links Euphorbiaceae genera Crotonoideae Flora of South America Rubber