Phenetic relationships of some Poaceaus genera were studied. Plants representing these genera were; Quack grass, Wild oat, Barley, Rice, Millet or wild proso, Canary grass, Sorghum, Johnson grass, Wheat and Corn. Comparative anatomy of surface features of the leaves was used as a taxonomic evidence to establish their phenetic relationships. Scanning electron microscopy technique (SEM) was used to compare the leaf   suture features of the above plants. The studies concentrated on some of these features; i.e. short cells, long cells, interstomatal cells, silica-bodies, stomata and hair types. Through the observations, it was possible to detect the taxonomical relationships among the studied taxa, which could be summarized as follows; some taxa showed greater similarity to each other due to sharing most of the examined features; i.e. Rice, Millet, Corn, Johnson grass, Wheat and Canary grass. Some other taxa exhibit similarity but to a lesser degree; i.e. Barley and Wild oat, Rice and Quick grass, Barley and Canary grass, Millet and Wild oat and finally, Rice and Sorghum. On the contrary, The third pattern of taxa which were far away from each other due to sharing only in one to three characters; i.e. Sorghum either with Canary grass or with Johnson grass.