This book reports all papers published in "2003 International Symposium on Plant Growth Modeling, Simulation, Visualization and their Applications (PMA03)" held at Beijing, China, in October 2003. It covers multidisciplinary exchanges around real and virtual plant modeling and their applications in botany, agronomy, environmental sciences, computer sciences and applied mathematics. Scientists, engineers, researchers and university students concerned by tree/plant architecture and functional modeling, simulation, visualization and their applications in various fields will find useful lectures and examples from theory and practice in this book. The total of 40 papers (including 4 invited papers) present recent advances of studies in the following areas: - Modeling and simulation of plant structures and functional processes, - Modeling and simulation of environmental factors and processes (soil, climate) on plant growth, - Applications of crop modeling in agronomy - Applications of tree models in forestry and land use, - Methodologies for sampling, measuring and digitizing, - Visualization and computer graphics applied to virtual plants and landscapes.