The pathogenic fungi causing leaf spotting of several species of ornamental plants were isolates, diagnosed and purified. a (229) fungal isolates belonging to several fungal genera was obtained and the species belonging to the genus Alternaria were selected to conduct experiments on them. Where (89) isolates of the fungal type Alternaria dianthi and (68) isolates of the type A.alternata were obtained in addition to three isolates of the type A.longipes and one isolate of the type A.radicine. The phenotypic qualities represented by the forms of colonies, which are considered evidence in classification and innate diagnosis, have also been studied, and the colors of colonies belonging to this genus ranged from dark olive to pale in addition to some other phenotypic qualities such as the emergence of the phenomenon of sectors characterized by some fungal isolates.