Owing to the importance of photosynthesis to the efficient functioning of plants as solar energy collectors, scientists have been intensively studying the process of photosynthesis for more than 100 years, with the hope of increasing its efficiency. There is substantial evidence that fruit trees distribute their nutrient resources and photosynthetic competency, and adjust the angles of leaves in different parts of their canopy to optimize use of resources and sunlight as it passes through a tree canopy. This chapter examines the factors that influence photosynthesis in fruit trees, as well as the four key principles governing the distribution and use of photosynthates. Finally, the chapter looks at the features of fruit tree canopy architecture.