This is the first stage of a plant's life. Of course seeds won't just grow on their own. They need a little help from water, sunlight, and carbon dioxide. Seeds are usually planted in soil where they can receive sunlight and water when it rains.
This is the germination stage. This is when a seed beings to grow, or sprout. The embryo inside the seed pushes out through the seed coat. With more water and sunlight, the seed will continue to grow.
The embryo begins growing roots and pushes downward into the ground. The top half of the embryo will begin to grow leaves and push up through the soil to reach the surface of the ground.
A seedling is a young plant. During this stage, carbon dioxide starts to become important. The leaves use this gas to make their own food. Leaf cells breath the gas in and turn it into sugar through a process called photosynthesis. This sugar becomes food for the plant.
This is the young adult plant stage. These plants are bigger than the seedling with more leaves. They still use sunlight, water, and carbon dioxide to continue to grow.
This is the adult plant stage, which is the final stage of a plant's life. It is fully grown and is now old enough to reproduce. Once a plant can reproduce, the life cycle can state all over again, starting with a seed.