This title discusses the role of plants in combating desertification. Desertification - the degradation of soils in drylands - is a phenomenon occurring in scores of countries around the globe. The number of people (in semiarid regions) affected by the steady decline in the productivity of their lands is in the hundred millions. This work provides the reader with the experience of scientists from 30 countries and international institutions around the globe, working in cold and warm dry regions to bring plant-based solutions to one of the most severe problems of our times. The measures required to halt or reverse the process of desertification fall into many categories - policy, institutional, sociological/anthropological, and technical.