Trees are the largest of all plants. They can grow as high as a 30 story building, and live much longer than other plants. Some trees live for thousands of years, and are known as the oldest living things. Trees continue to grow for as long as they live.
Leaves of a tree are useful by providing food to the tree, keeping it alive and to continue to grow. Where winter's are cold, many trees lose their leaves in autumn. Other trees keep their leaves during the winter and stay green all year long. Trees that shed their leaves in autumn rest during the winter, and when spring comes, they grow new leaves and flowers. Flowers will grow into fruit which contain seeds for producing new trees, for example Orange and Apple trees.
A tree differs from other plants in four main ways:
1. Most trees grow at least 4.6 to 6.1 meters tall
2. They have one woody stem called a trunk
3. The stem grows at least 3 to 4 inches thick
4. A tree's stem can stand by itself
All other plants differ from trees in at least one of these ways.
Trees can be categorised into six main groups:
