Introduction -- Cyanobacteria: Habitats and Species -- Cyanobacteria: Multiple Stresses, Desiccation Tolerant Photosynthesis and Di-nitrogen Fixation -- Eucaryotic Algae -- Lichens and Bryophytes - Habitats and Species -- Ecophysiology of Desiccation/Rehydration Cycles in Mosses and Lichens -- Lichens and Bryophytes - Light Stress and Photoinhibition in Desiccation/ Rehydration Cycles: Mechanisms of Photoprotection -- Evolution, Diversity and Habitats of Poikilohydrous Vascular Plants -- Ecophysiology of Homoiochlorophyllous and Poikilochlorophyllous Desiccation-Tolerant Plants -- Hydraulic Architecture of Vascular Plants -- Drought, Desiccation and Oxidative Stress -- Chamaegigas intrepidus DINTER - an Aquatic Poikilohydric Angiosperm that is Perfectly Adapted to its Complex and Extreme Environmental Conditions -- Molecular Biology and Physiological Genomics of Dehydration Stress -- Dehydrins: Molecular Biology, Structure and Function -- Understanding Vegetative Desiccation Tolerance using Integrated Functional Genomics Approaches Within a Comparative Evolutionary Framework -- Resurrection Plants: Physiology and Molecular Biology -- Synopsis. Desiccation tolerance was essential when plants first began to conquer land, roughly 400 million years ago. While most desiccation-tolerant plants belong to basal phylogenetic taxa, this capacity has also evolved among some vascular plant species. In this volume renowned experts treat plant desiccation tolerance at the organismic as well as at the cellular level. The diversity of ecophysiological adaptations and acclimations of cyanobacteria, eukaryotic algae, mosses, and lichens is addressed in several chapters. The particular problems of vascular plants during dehydration/rehydration cycles resulting not only from their hydraulic architectures, but also from severe secondary stresses associated with the desiccated state are discussed. Based on the treatment of desiccation tolerance at the organismic level, a second section of the book is devoted to the cell biological level. It delineates the general concepts of functional genomics, epigenetics, genetics, molecular biology and the sensing and signalling networks of systems biology involved in dehydration/rehydration cycles. This book provides an invaluable compilation of current knowledge, which is a prerequisite for a better understanding of plant desiccation tolerance in natural as well as agro- and forest ecosystems where water is one of the most essential resources.