According to recent estimates, the palm Bora of the Old World comprises about 1566 species arranged in 125 genera. The distribution of this diversity is by no means even. with the African continent being surprisingly poor, while other areas such as Sundaland (Malay Peninsula, Sumatra, Borneo, Java, acid Palawan) are very diverse. Diversity, measured purely by numbers of species, is not only affected by the degree to which the palm flora is known but also by the broadness or narrowness of the species concept used. A variety of species concepts have been applied to Old World palms. There is a tendency for narrow species concepts to be used in the early stages of exploration of a given geographical area. Narrow concepts also tend to be used when local variation is described without reference re, the overall variation of a taxon. When broad monographic studies are completed, local variants often become subsumed within wide-ranging variable taxa, and this may lead to dissatisfaction with the taxonomy from local botanists who can recognise perfectly distinct forms. Examples of broad and narrow species concepts are provided and the utility of the different approaches discussed. Examples of species complexes or "ochlospecies" are provided to illustrate the intractability of accounting for variation with conventional methods. The broad general differences in diversity between geographical areas will be discussed, together with possible causes.
