Leaves are a very important part of plants. They use sunlight to make food for the plants. The food helps the plant grow, make flowers, fruits, seeds, and new leaves.
Most trees have no leaves, but they have many buds.
Tiny leaves are protected inside the little bud cases. The trees are resting during the Winter. In the spring the trees start warming up as the weather changes. Sap begins to flow up the trees to the buds. The buds start to swell.