| Trees use energy in the processes of their own living | | | | which are recognized as the most important and the |
| and in manufacturing carbohydrates, oils, hormones, | | | | most extensive chemical reaction system taking place |
| vitamins and other essential substances. These are the | | | | on earth. Photosynthesis is the basic life reaction that |
| basic foods for all living things, including themselves. A | | | | powers the life processes of all living things. |
| tree gets its nourishment from carbon dioxide in the air, | | | | Man is no exception to this rule. When we eat we |
| absorbed through its leaves, and from salts in the soil, | | | | obtain from our food the energy to live and to work |
| dissolved in water and absorbed through its roots. | | | | whether we consume plants directly, or indirectly |
| Carbon dioxide enters the leaves through the stomata; | | | | through the body of another animal. The source of that |
| in the presence of chlorophyll, activated by the energy | | | | energy in sunlight made available through the |
| of sunlight and using water absorbed by the roots, | | | | photosynthetic green plants. As the photosynthetic |
| carbon dioxide is converted into food for the tree. | | | | reaction proceeds, oxygen is produced as a byproduct |
| This process of trapping energy from sunlight and | | | | and it is now recognized that the oxygen of the |
| building it into chemical compounds is called | | | | Earth's atmosphere has been largely produced from |
| photosynthesis and can be carried out only by green | | | | this source. Trees must have played, and still do play, a |
| plants. It consists of a series of chemical reactions | | | | most important role in this process. |