Pollen morphology of the genus Begonia in Africa

The morphology of the pollen grains of African Begonias is described, leading to the recognition of 15 pollen types. These pollen types are assumed to constitute natural units produced by evolution and the main purpose of this study has been to reconstruct the course of evolution and to apply the resulting insights to the various taxonomical problems. It has been attempted to formulate a critical approach to the problem of applying pollen-morphological data to phylogenetic reconstruction. The evidence from pollen morphology is compared with that from other disciplines, viz. seed morphology, the study of placentation types, karyology and, especially, macromorphological taxonomy. The relation between pollen morphology and geographical distribution is discussed, while the pollen morphology of Madagascan Begonias as well as of the allegedly related family of the Datiscaceae is also investigated.