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 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

El Sohol area is lie north of Ibb city and Al Ta'akr mountain of Ibb with altitude 3000 m above sea level and lie south of Ibb city. This study is a phytosociological comparison between two areas which differ from each other in topography: A total of 111 species belonging to 51 families of were recorded in 29 sites of the studied area.Family Asteraceae was the most abundant family, comprising12 species. The families Acanthaceae and Euphorbiaceae represented by 6 species, each Lamiaceae represented by 5 species and Mimosaceae. Moraceae and Poaceae were represented by 4 species. The plant life form of the studied area showed that the highest recorded life form was for Phanerophytes constituted species representing 37 % of the total species followed by the chaemophytes with 28 species representing 25 %. Therophytes with 26 species representing 23 %. Cryptophytes with 13 species representing 11 % and Hemicryptophytes with only 2 species representing 1.8 % of total species of the work. From AlTa'akrmountain we can summarize the following: Community in plateau dominated by Pennisetum setaceum,near plateau was dominated by Rosa abyssinica in medium and high slopes, also very steep slopes were dominated by Hypericum revolutum, Wadi El Ganat communityArundo donaxwas dominated by in wadi bed, Ziziphus spina-christi dominated in the terraces , Acacia melifera and Acacia etbaica dominated in slopes.In Najed El El Bard,Ziziphus spina-christi dominated in wadi bed , Acacia asak dominated in the terraces of wadi,Acacia etbaica dominated in low slopes of wadi, and Acacia melifera dominated in medium slope of wadi.In El Gabal El Akhader .Ormocarpum dhofarense dominated the low slopes Euphorbia inarticulate dominated in medium slope and plateau of mountain,whileCynodon dactylon high slopes. DECORANA was used to clarify relations among environmental factors and plant distribution.