This document summarizes a study that examined how the physical, chemical, and metabolic characteristics of sugar maple leaves vary with their depth in the tree crown and with the addition of nutrients. The study found that foliar nitrogen and chlorophyll increased deeper in the crown and with nitrogen addition, while foliar phosphorus increased with phosphorus addition. The study concludes that most leaves are shaded rather than just "sun" or "shade" leaves, and that examining the vertical gradient in a tree crown can help reveal relationships between leaf characteristics and nutrients.