Comparative studies of Drepanopeziza species pathogenic to poplars established that for each species, holotype and herbarium specimens of D. populorum, D. tremulae and D. punctiformis were morphologically similar. Light and electron microscope studies of apothecia revealed that in radial longitudinal section, in apothecial shape and the hypothecial and epithecial tissues of the three species were similar. In general, ectal and medullary excipular tissues of D. populorum were more strongly developed than those of D. tremulae and D. punctiformis. Asci and ascospores of D. populorum were larger than the other two species but because of overlap were of limited use for species delimitation. In consideration of the established synonymy of the anamorphs of D. tremulae and D. punctiformis namely, Marssonina tremulae and M. brunnea, respectively, and close morphological similarity of their teleomorphs, synonymy of D. tremulae and D. punctiformis is suggested, with D. tremulae having priority. Although not studied, D. populi-albae is believed to be a distinct species. Accordingly, three Drepanopeziza holomorphs are recognised on poplars: D. populi-albae, anamorph=M. castagenei; D. populorum anamorph=M. populi; and D. tremulae, anamorph=M. brunnea.