This volume highlights fungal associations, as they are found in mycorrhizas, lichens and other fungal symbioses. The emphasis is laid upon the molecular, biochemical and ultrastructural analysis of these interactions. Major progress has been achieved over the last few years by the systematic application of modern methods, developed mainly in molecular biology. The data are presented in high-quality illustrations, leading the reader from the subcellular to higher levels of organization where specific symbiotic traits become apparent. Early stages of symbiotic interactions are of special interest. They are compared to parasitic interrelations and also considered from an evolutionary standpoint.