Since their discovery over 100 years ago, plasmodesmata have been the focus of intense investigation. Plasmodesmata are unique to plants and form an intercellular continuum for the transport of solutes, signals and ribonucleoprotein complexes. It is now clear that plasmodesmata formation and regulation are central to a diverse range of plant functions that include developmental programming, host-pathogen interactions and systemic RNA signaling. This book provides a state-of-the-art overview of the diverse forms and functions of plasmodesmata. It covers the structure and evolution of plasmodesmata, their role in plant development and solute transport, and their central function in systemic signaling via the phloem. It includes critical evaluations of current methods used to study intercellular transport via plasmodesmata. The volume is directed at researchers and professionals in plant cell biology, plant molecular biology, plant physiology and plant pathology.