Leaves play several roles in maintaining plant health.
- Leaves are the location of photosynthesis, the process by which plants convert sunlight (thermal energy) into sugars (chemical energy) that the plant uses for food.
- The underside of a leave contains many small openings called stomata. Water evaporates in the spongy mesophyll of the leave and water vapor exits the leaf through the stomata. This creates a vacuum within the plant that pulls water up through the plant from the roots.
- Many plant wastes are stored in the leaves. As the leaves die and fall off the plant, the plant is able to get rid of wastes.