Fungi are amongst the simplest of eukaryotes. Their study has provided useful paradigms for processes that are fundamental to the way in which higher cells grow, divide, establish form and shape, and communicate with one another. The majority of work has been carried out on the budding yeast Saccharomyces cerevisiae, but in nature unicellular fungi are greatly outnumbered by filamentous forms for which our knowledge is much less well developed. This volume focuses on the analysis of the filamentous life style, particularly on the hyphae which constitute the fungal mycelial colony. It provides the most recent insights into the molecular genetics and physiological mechanisms underlying the elaboration of the branching mycelium and the interactions between individual fungal mycelia. As such it offers much to interest mycologists and, equally, those working in the fields of cell biology, developmental biology, physiology and biochemistry.