Hyphal structures of A, zinniae were seen in the cross sections of various parts of inflore­scences. Infection lead to disorganization of epidermal and parenchyma tissues of petal, involucre of bracts, ray and disc florets. Destruction of pollen grains was quite evident. HistochemicaJ analysis in the diseased tissues revealed marked differences in total protein but not in total insoluble polysaccharide and RNA content. The fungus utilized starch granules from the host.