How Plants Of Tropical Africa Feed

WE have seen quite clearly that plants are alive, just as much as animals are, although their ways are different. They require to feed and need air to breathe and water to drink just as animals do. They grow old and die, and to continue the race they produce seeds which grow into the new plants. In order to obtain food, air and water, all living things set aside certain parts of their bodies each for its special work. Thus an animal breathes with its lungs, eats and drinks with its mouth, and grasps with its hands. A plant has no lungs, mouth, hands or feel. What, then, has it to take the place of these? If you dig up a plant and look at it you will find that it consists of a part which lives in the soil called the root, and a part above the soil which is the shoot and which consists of the stem and leaves. In addition to the leaves the stem bears buds and often flowers and fruits. For the plant to feed and grow, the root, 51cm and leaves are necessary. 

The flower produces fruit and seeds, and the latter produce the new plants. Let us see, first of all, how feeding is carried out by the root, stem and leaves. To start with we may think of the root as the mouth of the plant taking hi the food; but you must not think that the root eats solid food, for this it cannot do. What it does is to suck in, by means of very tiny hairs that cover it, the water all round it. Now, this water has substances out of the soil dissolved in it. When sugar is dissolved in water, and we drink it, we know that we are getting the sugar as food into our bodies. Just the same happens with plants; the substances dissolved in the water round the roots are absorbed by the roots and pass into the plants as food. The next thing that happens is that this food still dissolved in the water passes up the stem by a kind of "soaking process," and at length gets up to the leaves.

This "soaking process" may be said to be like the method by which kerosene oil passes up a lamp wick. Now, the leaves are very important. To start with, they are, as you know, usually green This green color is due to a substance called Chlorophyll in the them. In addition they have extremely small opening called " stomata" all over them, especially underneath; you cannot see these openings because they are so small, but through them air is taken in. Not only is this air used for breathing, as in animals, but in it is a gas called carbon dioxide, and this, together with the substances taken in by the roots from the soil, makes food for the plant.

A very wonderful process goes on in the leaves which you may think of as a kind of cooking process, but it is really more wonderful, as in it the non-living substances of the soil and the carbon dioxide of the air are so blended together by the chlorophyll and by the help of the sunlight that living substances am formed which get carried all over the plant to make it group How this really happens is not exactly known, but the fact remains that starting with non-living material out of the soil and the air, the living tissues of the plant are formed, living because they make the plant grow and produce more leaves, stems and flowers. It is most important to remember about chlorophyll, because without it none of this could happen. Sunlight is, of course, equally important, because it is due to sunlight that the chlorophyll is formed at all. A plant will grow for a short time in darkness, but it will soon die, and while it lives it will remain yellow or white instead of green.

There is another thing that the 'eaves do beside, taking in part of the air, and converting the food into living tissues: that is, they get rid of the water that the plant takes in and does not want any more. A plant needs a certain amount of water for itself, but very much more water is taken in by the roots than the plant wants, chiefly for the sake of the food that is dissolved in it. Now this excess of water must be got rid of, and this is done by the leaves through the stomata.

The water is given off by the plant as water vapor, and this vapor mixes with the air, making it moist and damp. Some plants will in this way give off a great deal of water every day, and large trees may give off several gallons; in this way the air round a forest or in a plantation is very moist indeed. This giving off of water takes place mainly during the day, but also to a small extent at night.

To put it briefly, a plant is fed by the root, stem and leaves, in the following way: By the root, by means of the root hairs taking in food dissolved in water from the soil. By the stem passing the food dissolved in water up to the leaves. By the leaves: 1. By means of the stomata taking in the carbon dioxide from the air. 2. By means of the chlorophyll and the sunlight building up living tissue from the food brought by the roots and from the carbon dioxide of the air. 3. By means of the stomata giving off the water which has been used as a carrier for the food and which the plant no longer needs for itself.