SummaryDischarge and germination of ascospores ofHypoxylon mediterraneum(=Biscogniauxia mediterranea(De Not.) O. Kuntze) were studied. Discharge and germination of ascospores depend on the presence of water or high relative air humidity. Ascospores are ejected from stromata in forest for most of the year following periods of high precipitation.H. mediterraneumascospores germinated under a wide range of biotic and abiotic conditions. The optimal temperature for germination was 35°C, but 25 and 30°C were still favourable, while 20 and 40°C reduced germination. Ascospores kept at 5°C were able to germinate after short exposure to temperatures ranging from 20 to 35°C. Germination rate depended on the ascospore density inin vitroexperiments, and was highest at 106ascospore/ml.Tissues of some host plants greatly increased germination rate.In vivo, ascospores germinated better on wounded axillary tissues than on unwounded