Leaves are adapted for carrying out photosynthesis by virtue of their flat shape and periodic replacement, and because they contain most of the plant’s chlorophyll. Leaves are the primary location in which photosynthesis occurs, so plants often arrange their leaves to receive the most solar radiation.
Because they are flat and thin, leaves have a very high surface to volume ratio. This means that the plant does not have to produce very much material in order to absorb a lot of sunlight. Additionally, because the leaves are flat, they yield to wind and rain, which allows them to last longer on the plant.
Most plants replace their leaves periodically as the old ones become damaged or eaten. This ensures that the plant has a full complement of energy-producing leaves. However, during the cold and dry winter, many plants drop their leaves to prevent desiccation. When the humidity level rises again, the leaves regrow and restart the process of photosynthesis.
The chemical chlorophyll gives plants their green color. This chemical is one of the necessary components for photosynthesis. As the leaves receive the most sunlight, and their surface area is quite large, they are the most efficient location for photosynthesis to take place.