Wadi Khulab considers one of the most important wadis in Jazan, southwestern 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.

Aims: To study vegetation, life-form and chorotype to assess the species diversity between the different community types. Study Design: Several field trips were carried out to the study area. Place and Duration of Study: Wadi Wasaa -Jazan -Saudi Arabia. Methodology: Vegetation diversity, chorology and abundance values were visually estimated and used to form ten clusters of plant community types by statistical methods with Euclidian Distance and Ward method using SPSS program (ver.20). The Shannon-Wiener diversity index was used to estimate diversity, richness and evenness of the recorded species. Results: A total of 95 species belonging to 75 genera and 31 families were recorded. Poaceae and Euphorbiaceae both are the dominant families constituted 23% of the total species followed by Apocynaceae, Malvaceae. Chamaephytes and therophytes were the prevailed life forms, indicating a typical desert life-form spectrum (chameo-therophytic) type. The chorological analysis revealed a total of 26 species representing 27% fall under monoregional, 56 species (59%) as biregional area Original Research Article

Aims: To study Floristic diversity, life-form, chorology, edaphic factors affecting the species distribution of Wadi Qusai. Study Design: Several field trips were carried out to the study area -sites soil analysis. Place and Duration of Study: Wadi Qusai -Jazan -Saudi Arabia. Methodology: Floristic composition, vegetation diversity, life form, chorology, soil analysis and cover estimation by TWINSPAN, DCA and CCA. Results: A total of 103 species belonging to 77 genera and 33 families were recorded from 20 sample sites. Poaceae, Euphorbiaceae and Amaranthaceae are the most highly represented families. Therophytes and phanerophytes are the dominant life forms. Chronological analysis revealed that biregional elements that belong to the Saharo-Arabian and the Sudano-Zambezian together have the highest share of species representing 36 species (35% of the total species). Conclusion: Five vegetation groups were recognized by TWINSPAN, DCA and CCA analysis; group A (Aloe fleurentiniorum, Cadaba glandulosa and Delonix elata) inhabiting the high wadi slope, group B (Anisotes trisulcus , Fagonia indica, Pulicaria undulata, Acacia ehrenbergiana and Panicum turgidum) was occupied the low slope and wadi terraces, group C (Ziziphus spina-christi, Abutilon pannosum and Fagonia indica) was represented the medium wadi slope, Group D

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