About Trees

About Trees

Introduction Trees are the tallest living plants. Redwood trees can grow as tall as a 30-story building. Giant sequoias can weigh as much as 3, 000 large pickup trucks, making them one of the heaviest living things. Trees also live a long time. Many trees alive today were full-grown long before the United States became a country. But these massive trees share something with all plants-they make their own food.

Leaves Imagine being able to make your own food without cooking or even going to a restaurant! Leaves make food for trees by changing energy from sunlight into food. This important work is done by chlorophyll (KLOR-uh-fill), the green coloring in leaves. Leaves come in all shapes and sizes. Most deciduous (dee-SIJ-oo-us) trees have wide, thin leaves, while most conifers have needlelike leaves. Conifers keep their needles through all seasons. Only the oldest needles fall to the ground. Deciduous trees lose their leaves every fall.

In the fall, the leaves of deciduous trees show their true colors. These true colors are yellows, oranges, and browns, which hide under green chlorophyll all spring and summer. We see these colors in the fall after leaves stop making chlorophyll.

Branches Branches are the arms that hold up a tree's leaves. Branches spread leaves out to get as much sunlight as they can. The leaves give shade to other living things on sunny days. Branches start out as twigs, then they grow thicker each year. As a tree grows, its bark cracks open so the branches and trunk can expand. New bark is always growing under the old, ready to protect the tree. If new bark gets stripped away, a tree can die.

Trunk Tubes in the tree's trunk carry water from the roots up to the leaves. They also carry sap, or food, down from the leaves to the roots. These tubes are like highways, carrying traffic back and forth. They are close to the outside of the tree, just under the bark.