Abstract
The resin-producing genus Hymenaea has an amphi-Atlantic distribution with 13 species being Neotropical and one occurring along the eastern coast of Africa. Present evidence suggests an African origin for the genus with migration across the Atlantic occurring during the Early Tertiary when the continents were closer and rainforest vegetation was considerably more widely distributed than today. The center of its Neotropical distribution is the Amazonian hylaea, although within its extensive range from 23° N to 26° S it is found in all major ecosystem types. The taxonomy, breeding structure, ecology and resin chemistry of the 9 Hymenaea species and 6 varieties occurring in the Amazonian and historically-related Brazilian Atlantic coastal humid evergreen forests are discussed as well as the possible evolution of these species in response to postulated drying trends beguen in Mid Tertiary times and during wet-dry oscillations in the Pleistocene.