This publication is the 21st volume in the British Mycological Society Symposia Series and documents the proceedings of a symposium held in September 1997. The book is devoted to filamentous fungi, highlighting the complex biological behaviors that can emerge from growth in the form of interconnected, branching hyphae. Within thirteen chapters the book covers a broad range of topics from the development of cell compartments within hyphae to mathematical models of colony pattern development. The initial chapter provides a theoretical discussion of boundary dynamics and its relationship to development of mycelial growth patterns. This was a daunting introduction and difficult to digest without an appreciation of the growth patterns and behaviors discussed in subsequent chapters. It would have better served as a generalized conclusion to the book. Several subsequent chapters consider environmental effects on mycelial growth patterns and development. These explore the consequences of heterogeneous nutrient distribution, characteristic of a soil habitat, the relationship of nutrient supply to hyphal differentiation, the effect of toxic metals and nutritional stress, nutrient translocation within mycelia, and the possible role of electrical signaling in coordinating the behavior between distant elements of the mycelium. An additional chapter covers the molecular mechanism and colonial consequence of circadian rhythms. Mycelial development depends ultimately upon the polarized growth, septation, and branching of hyphae. These cellular processes are considered in several chapters, which include the genetic control of polarized growth, the genetics of septation, the role of phosphoinositides in signaling and controlling these processes, and the effect of submerged culture on mycelial branching. Fungal colonies interact not only with their environment, but also with each other. One chapter is devoted to extracellular signals required for mating and another chapter explores a unique molecular mechanism regulating gene expression in dikaryotic hyphae formed during mating. In contrast to the genetic flux attendant to mating, genetic stability is critical to fungal colonies since some natural fungal colonies are estimated to be as much as 1500 years of age. The penultimate chapter explores this topic. The book contains a useful, though not exhaustive index. The book will be of general interest to mycologists, but may be somewhat inaccessible to general audiences. Attention to fungal terminology and more explicit descriptions of experimental systems would have benefited the non-mycologists. The broad range of topics both limits the depth of coverage within a topic area and affords an appreciation of the rich complexity of the fungal colony. In this regard the book achieves its objective of bringing forth an appreciation of the multi-faceted behavior of fungal growth and recognition that “the whole mycelium exceeds the sum of its hyphal parts”. The book may stimulate mycologists focused on the fungal cell to expand their consideration of fungal growth and, conversely, give those studying the large-scale behavior of fungi an appreciation of the cellular basis of mycelial development.