Article,

Analysis of the Flora of Mediterranean and Saharan Africa

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Annals of the Missouri Botanical Garden, 65 (2): pp. 479-534 (1978)

Abstract

After defining the state of knowledge and reviewing national inventories, the author looks at the reasons which led him to study Mediterranean and Saharan Africa and to detail their biogeographical significance. For Mediterranean and Saharan Africa, the generic and specific richness, the richness of endemics, and the entire biogeographical range are first analyzed at the family level. In the second part, the various biogeographical elements which play a part in the formation of the floras at the generic and specific levels are defined; several examples are provided respectively for the Mesogean (Mediterranean, Saharo-Arabian and Irano-Turanian) and tropical elements. A third part is devoted to endemism: first generic and specific endemism, then the biogeographical significance of the endemic taxa. It appears that the flora of Mediterranean Africa is about three times richer than that of Saharan Africa and that endemism there is two times greater. Whereas the flora of Mediterranean Africa is for the most part made up of Mediterranean taxa, in Saharan Africa there is a nearly equal distribution of Mediterranean, Saharo-Arabian, and tropical elements. These characteristics are related to the hostile ecological conditions which govern the Sahara now, but also reflect the climatic disturbances which took place during the Pleistocene. A special chapter is devoted to a discussion of the historical interpretation of the flora of Mediterranean and Saharan Africa, taking into account the new data provided by paleoclimatology and paleobotany. It is concluded that the Mediterranean flora is relatively old and goes back at least as far as the middle Miocene, whereas the present Saharan flora is a reflection of intense climatic changes which have severely affected this region since the Pliocene. In each of these cases emphasis has been placed on the role elements of African origin played in the development of the present flora.

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