Floristic Compositions and Its Affinities to Phytogeographical Regions in Wadi Khulab of Jazan, Saudi Arabia

Wadi Khulab considers one of the most important wadis in Jazan, south-western Saudi Arabia. Thus the current work provides an analysis of the floristic composition, life form and chorology of plant life of the wadi, a total of 119 species related to 93 genera represented 44 vascular plants families were documented. Six families (Aizoaceae, Euphorbiaceae, Papilionaceae, Poaceae, Amaranthaceae and Asclepediaceae) provided nearly half of the total number of species reported. Therophytes and chamaephytes are the most frequent life forms which may indicating a typical desert spectrum vegetation. The floristic composition of the different geomorphologic landscape units offered differences in species richness in the different sectors of the wadi, and the phytochoria. Monoregional and biregional areas contained 45 species (41%), while biregional species were 39 species (36%) respectively, while only two species (2%) were recorded in the pleuriregion. It is thus concluded that the region should be considered a hot-spot in the Kingdom in terms of floral diversity.