Roots Of Tropical Africa

WE have Seen how the root is that part of the plant which lives underground; we have also found that it is by means of the root that the plant takes in its food from the soil. The root is the first part of the young plant to grow out of the seed. Some plants have one strong root which grows straight down into the soil with branches growing out of it; this main root is called a taproot The root of the bean is an example of a tap-root Sometimes the tap-root of the plant becomes very much swollen or enlarged, and inside it is stored reserve food material; such swollen roots are known as tuberous roots, and examples of this are the roots of cassava, sweet potato, etc.

The reserve food material stored up in such roots is used up during the second Season of the growth of the plant, when the flowers and seeds are being produced. Such plants as these are very useful to us for food, as most of such roots can be boiled and eaten as vegetables, or in some cases ground into flour and made into cakes.

Other plants have no main central root, but a number of stringy roots, arising from the bottom Of the stem. Such roots are called fibrous roots. The roots of the maize, all grasses, bamboos, palms, etc., are fibrous roots On very young roots, and later on the branches of roots, there are bunches of fine hairs, called root-hairs. These root-hairs are difficult to See in a plant grown in the soil, for when the plant is pulled up the root-hairs are generally destroyed. They can, however, be very well seen in the root of a bean if it is grown in a jar over water.

These root-hairs, although they are so small, are very important; it is by means of the root-hairs that plants take in the food and water from the soil. It is most important to remember this when transplanting a plant, and to keep enough soil around the root-hairs to keep them well protected. The tip of a root is a little different from the rest; it is slightly swollen and generally of a darker color. This is due to what is called the root cap, which is a thimble-like covering over the growing point Of the root to protect it when it is forming its way through the soil. Roots always grow downwards, away from light and towards any moisture that may be near. The root of a plant, as well as gaining food and water, also serves to hold the plant in the soil; that it does this can easily be tested by trying to pull up a plant It is necessary for plants to be firmly fixed in the soil so that they can hold the stem erect and allow plenty of sunlight and air to get to the leaves.

The roots also prevent a plant being blown down by the wind or washed away by the rain. The larger the stem of a plant is, the larger must its roots be; the cotton tree, for example, with its great stem, has large roots extending outwards and downwards deep into the soil. Many plants not only have the original roots that grow from the bottom of the stem, but also may have extra roots which spring from higher up the plant; this happens in the case of plants which require extra support. The screw-pine is a very good example of this and often shows many roots branching off from the side of the stem; these adventitious root, as they are called, act just the same as ordinary roots under the soil, but the portion above the soil becomes like a small stem both inside and out trees all send down roots from their branches to act as supports. Another well-known example of a tree with aerial roots in Tropical Africa is the mangrove; such roots are necessary because of the muddy soil in which the plant grows. Roots will often grow from the cut ends of steams and because of this certain plants can be grown from cuttings (i.e., pieces of stem cut off and stuck in the ground). In some cases roots will even spring from the leaf of a plant; thus if a begonia leaf be pinned down flat on soft, moist soil, it will develop roots and eventually will grow into a complete plant Orchids give off roots from their stems, but their roots do not always serve for extra support to the plant as they swing about in the air and take in nourishment from the water that drops upon them off the tree upon which they are growing