When exploring nature, many observers notice that plant leaves adapt to their environment. As a plant grows, some leaves are exposed to the sun and other remain shaded. Typically, shaded leaves are located underneath sun leaves, and sun leaves are thicker. The different light conditions lead to physical changes in the structure of shade leaves and sun leaves.Generally speaking, shade leaves are the largest leaves of a plant. While shade leaves are bigger, sun leaves are thicker than their shaded counterparts. The differences in physical structure are caused by the cellular makeup of the leaves, according to the Oxford Journals website.