Abstract
During field studies in sand dune areas and some habitats close to wetland ecosystems of the Tihama region of Jazan Province in south-western Saudi Arabia, specimens of 3 interesting species belonging to the genera Odyssea (Poaceae), Sesbania (Papilionaceae), and Sesamum (Pedaliaceae) were collected; they were identified as Odyssea mucronata (Forssk.) Stapf, Sesbania sericea (Willd.) Link., and Sesamum alatum Thonn. A review of the literature revealed that these tropical African taxa were never before recorded for the flora of Saudi Arabia. O. mucronata is represented by a relatively large isolated population. The other 2, S. sericea and S. alatum components of a semi wetland ecosystem and sandy areas, respectively are represented in the Arabian Peninsula by 2 relict populations. Morphology, habitat descriptions, illustrations, and taxonomic commentary of all 3 taxa are presented.