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Tree and shrub species of restricted distribution do not occur randomly throughout the vegetation types and geomorphological formations of eastern Africa, but rather, show distinct concentrations of high endemism. Four geographical areas of high endemism are considered, the Eastern Arc mountain forests, the Eastern Are rain shadow, the dry transitional forests of north-ease tropical Africa and the arid areas of north-east tropical Africa. Three types of endemics are recognised: phylogenetic relicts, geographical relicts, and those with closely related taxa in the same or adjacent regions. Species distribution patterns are concluded to be primarily due to tectonic events creating climatic changes, with areas rich in taxa of restricted distribution being climatically and geologically stable. In the stable areas, phylogenetic and geographical relicts occur in the same localities as taxa apparently derived by allopatric or sympatric speciation, suggesting that climatic stability is important both for survival of relictual taxa and for initial speciation. Stability may be the factor that creates the differentiation that is later interpreted as vicariance when the range of parental taxa is reduced. Geological heterogeneity leads to floristic heterogeneity, and may be important for local speciation.