This BioProvince (as defined by Armen Takhtajan) comprises Sahara the largest desert in the world. In an east-west axis it stretching from the Libyan Desert to shores of the Atlantic Ocean, but the northern and southern boundaries are less well defined. In the north there is a gradual transition to Mediterranean vegetation, while in the south there is a transition to tropical vegetation. However, its northern boundary roughly corresponds to the northern limit of date palm (Phoenix dactylifera) cultivation and the southern limit of Stipa tenacissima, one of the most characteristic species of the Mediterranean-Saharan transition zone, while its southern boundary more or less corresponds to the southern limit of Panicum turgidum, Stipagrostis pungens and the endemic Cornulaca monacantha (Chenopodiaceae). The substrate consists mostly of Cretaceous and Tertiary deposits but the crystalline bedrock breaks surface in a few places to form small mountain ranges such as the Ahaggar, Jebel Uweinat and Tibesti ranges, and locally elsewhere to form granite inselbergs. The desert areas include sand desert (erg), gravel desert (reg), stone desert (hamada) and dry valleys (wadis). There are also areas of lush vegetation (oases) where water issues as springs. With one of the harshest climates in the world the Sahara is dominated by two climatic regimes. In the north there is a dry subtropical climate that gives way to a dry tropical climate in the south. The subtropical areas feature high annual and diurnal temperature ranges with cold to cool winters and hot summers. The tropical areas are characterised by a strong annual temperature cycle with mild, dry winters followed by a hot dry season with variable summer rain. The flora in general is not particularly rich with just over 1600 species but about 12% of the species endemic, and there are some 16 endemic genera including Ammospermum, Amodaucus, Battandiera, Eremophyton, Foleyola, Lifago, Lonchophora, Monodiella, Muricaria, Nicularia, Oudneya, Quezelia, Tibestina and Warrionia.
The following accounts for this BioProvince have been written or will be written with particular reference to endemic and locally important species. Accounts available are displayed in green or yellow. Those displayed in red are either in the pipeline or awaiting expert contributions.
|Vascular Plant Flora|