AbstractThe systematics of the Armillaria mellea complex. Phytopathological consequences. The five biolo‐gical species of theArmillariacomplex as defined by Korhonen coincide with species already defined by other authors on the basis of their morphology and have been given latin namenelature.The main characteristies of the five Eurmpean species are deseribed: Fruitbody morphology, myce‐lium morephology in loboratory culture, rhizomorphs grown in a rhizotron and the ease with which fruithodies are produced in the laboratory. A descriptiom is given of the geographical distribution ecological specialisation and pathogenicity of these 5spec