Why Do Plants Need Sunlight?
Most plants, if placed where no light from the sun can reach them, will die very quickly. To prove that a plant needs the sunlight we have only to place it in a dark corner of the cellar and notice how soon it dies. In fact if it were not for sunlight there would be no life on earth at all. The plant or tree drinks in sunlight through the surface of the leaves. In fact the ability to take in sunlight constitutes the real life of the tree or plant. Leaves grow thin and flat in order that as much surface as possible may be exposed to the sunlight. If a leaf were curled up like a hoop only a part of the outside surface would be exposed to the sunlight and the amount of life that a leaf could supply to the rest of the tree would be much less. The leaf is so constructed that when the sunlight strikes down upon its green surface, it changes the carbonic acid gas which it drinks in, into its elements, i.e., it takes out the carbon which goes into the body of the plant and combining with other food and water supplied by the roots causes the plant or tree to grow and then returns the oxygen part of the carbonic acid gas to the air.