Trees have three main parts—crowns (canopies), trunks, and roots. Each part has a special job to do in keeping the tree healthy and growing.
The crown is the branches and leaves of the tree. It has the important job of making food for the tree. The leaves (the leaves of an evergreen are its needles) are tiny "factories" that make food using water absorbed by the roots and carbon taken from the carbon dioxide in the air.
Roots hold the tree in the ground and absorb water and minerals the tree needs to make food. Roots often spread much farther than the crown of the tree. Large, woody roots grow horizontally (side to side), mainly in the top 12 inches of the soil and usually no deeper than 3 to 7 feet. They often stretch out from the trunk to take up a space four to seven times larger than the crown! These roots spread across an area that can be twice the height of the tree.
The trunk and its branches give a tree its shape. The trunks of most evergreen (needleleaf) trees grow straight up to the top of the tree. All the branches grow out from the trunk. The branches near the top are shorter than those farther down, giving the trees a "Christmas tree" shape. The trunks of most broadleaf trees do not reach to the top of the tree. Instead, the trunk divides into spreading branches, giving the crown a rounded shape.