The Saharo-Sindian regional zone encompasses the flat and arid areas of North Africa, the Arabian Peninsula, southern Iran and the deserts of Pakistan and W India. There are some scattered mountains situated within this area like Hoggar in Sahara, Saint Catherine in Sinai and Genu and Homag in southern Iran. These highlands serve as interglacial refugia for cold adapted plant species. In the present study, phytogeographical patterns and relationships of the flora of Genu and Homag mountains are assessed and discussed in comparison to the phytogegraphy of the flora of low-lying Hormoz Island. According to chorological assesments of the flora, Genu and Homag mountains belong to theIrano-Turanian region with 59% of the species restricted to this area. However the surrounding lowland plains are part of the Saharo-Sindian area with a rather high proportion of the widespread species (17%) and Somalia-Masai linking elements (20%). It is noteworthy that several Turanian enclaves also occur in the lowland zone. Furthermore, the distributional evidences imply that the mountainous Irano-Turkestanian region is an integrated area which is supposedly distinct from the Turanian lowland areas in the North and the Saharo-Sindian lowland areas in the South. On the other hand, the expansive floras of Turanian and Saharo-Sindian regions are linked to each other. Endemic species in lowland areas in S Iran are mostly either frost sensitive vicariants of cold adapted Turanian species or of Saharo-Sindian origins, while the highland endemics in the area trace their origins to the Irano-turkestanian region.