While humans and animals eat plants and other animals for food, plants have the ability to make their own food. This process is called photosynthesis, and the leaves on a plant are where it begins.
Leaves are the food factory of a plant. Most plants and trees have thin and flat leaves, which work like solar panels to attract energy from the sun.
In the spring and summer, leaves are green because of a chemical called chlorophyll. The chlorophyll is used to trap energy they get from sunlight, which is used during photosynthesis.
Leaves need more than just chlorophyll to make food. Plants also must collect water from the soil and a gas called carbon dioxide from the air. They are then able to make their food, which is a kind of sugar called glucose. The process of photosynthesis also creates oxygen, which we breathe.
In the fall, the leaves on many trees and bushes change color because the chlorophyll begins to break down. When this happens, other pigments in the leaves cause them to turn shades of orange, yellow, red and purple.
In the winter, trees and plants that lose their leaves do not use photosynthesis to make food. They instead go dormant, which is similar to hibernation in animals. While dormant, they use food they stored during warmer months to help them survive until spring.