Recent studies that analyze the impact of various plant traits on whole-plant growth and competitive ability have provided insights into the selective pressures on characteristics such as leaf reflectivity, effective leaf size, stomatal conductance, size of photosynthetic enzyme pools, crown form, xylem structure, nitrogen fixation, and root versus shoot allocation. This research has reached an exciting stage, leading to quantitative predictions of favoured trends in these traits as a function of environmental parameters and fundamental physiological constraints. Such results reveal the importance of ecological patterns in plant form and physiology, and of evolutionary constraints on photosynthesis and primary productivity. On the Economy of Plant Form and Function summarizes the major recent advances in the economic analysis of plant behavior and suggests a framework for a unified, quantitative approach to understanding photosynthetic adaptations, their integration with other aspects of plant form, and their relationship to carbon balance and ultimate limits on plant productivity.