| Trees can be broken down into three main parts: the | | | | In planting or transplanting a tree, and in building on a lot |
| roots, the leaves and the woody structure between | | | | where you wish to preserve the trees, the gardener's |
| them. The roots' function is to bring raw | | | | chief consideration must be to protect the root |
| materials-water and mineral salt dissolved in water-to | | | | structure of the tree. The big roots near the stem |
| the tree. The leaves absorb carbon dioxide from the | | | | anchor the tree to the ground, while the fine root hairs |
| air and use the sun's light energy to combine this gas | | | | at the ends of the rootlets absorb the water from the |
| with the moisture from the roots, thus making the | | | | soil. |
| simple sugars that are the basic nutrients of the tree. | | | | The stem or trunk of a tree has three parts: the bark, |
| The trunk, limbs, branches and twigs hold the leaves in | | | | the wood and the pith. The pith is the central part and |
| position to receive the life-giving sunlight and air; they | | | | around it is the wood. Between wood and bark is the |
| also act as transportation, carrying raw materials | | | | cambium, a thin layer that produces new wood and |
| between roots and leaves. The materials absorbed by | | | | bark. When the cambium ring is severed, as by a wire |
| the roots are pulled up by capillary attraction and the | | | | cable, the tree is killed, and since the cambium protects |
| osmotic action induced by evaporation of water from | | | | against insects and disease, anything driven into it can |
| the leaves. Loss of water through the leaves is called | | | | wound the tree severely. |
| transpiration. | | | | Outside of man himself, trees have countless enemies. |
| On a summer day, a single birch tree may transpire | | | | There are 200,000 known kinds of insects that attack |
| 700 to 900 gallons of water. It is this enormous flow of | | | | trees, in addition to diseases such as blight, rust and rot, |
| water that causes a continuous flow of sap from the | | | | storms and droughts. Luckily, birds help to keep |
| roots to the topmost twigs. | | | | caterpillars, borers, beetles and other insects in check. |