Because of its growth features in vitro, pathogenicity and host relation, together with the ubiquitous wound- and weak-parasitic strains of Phoma exigua Desm. var. exigua, three more specialized pathogenic varieties of this species are distinguished: var. linicola (Naoum. & Vass.) Maas on flax, var. foveata (Foister) Boerema on potato, and var. sambuci-nigrae (Sacc.) comb. nov. on elder. The synonymy and the collective and differential diagnostic characteristics are discussed.