The Roots

Roots frequently make up one-half, or even more, of the weight of crop plants. The main functions of the roots are to anchor the plant and absorb water and plant nutrients from the soil.

All roots are alike in that they end in a rather hard pointed portion about a quarter of an inch long called the root cap. It is by means of this root cap that the young, tender root forces its way between the soil particles. The lengthening of the root takes place just back of the root cap rather than along the entire length, the root being in the soil. A fine, mellow soil is important in that it allows the roots to grow freely, as it is more easily penetrated by them.

Just back of the root cap are small rootlets, or root hairs ,which are feeding roots of the plant. It is through those hairs that the plant absorbs water and nutrients from the soil. The root hairs come into very close contact with the soil particles, as would be found, if a plant were dug up and the earth were washed from the roots carefully. It would be very hard to remove all the fine particles of soil from these root hairs , so closely do they cling. Wherever contact with a solid body is made, a special substance develops on the outside of the cell wall of the root hairs causing a very close contact between them and the soil particles, which makes possible a rapid absorption of moisture and nutrient materials. Root hairs may be an inch long, thought they are usually much less. They are short-lived, old ones dying and new ones forming continually. As the root gets older, root hairs cease to form.

Kinds of Root Systems

If we pull up wheat, oats, rye or some other cereal "by the roots" we observe a mass of roots arising at the base of the stem. The main roots of the cluster are approximately of the same size; each gives off numerous side roots, or roots of the second order, these, in turn, bear branches of the third order and so on.

All the roots arc slender and fiberlike; no one root is more prominent than the others. Such a root system is spoken of as a fibrous root system. It is characteristic of all the cereals (wheat, oats, rye, corn, rice, etc.) and other grasses, and many other monocotyledons.

Contrasted with the fibrous root system is that of such plants as carrot, beet, radish, turnip. These plants have one main root that grows directly downward, from which branch roots arise. A root system of this kind is called a tap root system.

The main or tap root of the above mentioned crops is a fleshy food-storing organ. In other plants, the main or tap root may not be fleshy but more or less woody, for example in oak, red clover, flax, lettuce, cotton etc. In general, fibrous root systems are relatively shallow whereas tap root systems may penetrate the soil to considerable depths. The root, like the stem, grows, conduct water and nutrients and stores food. Unlike the stem, it absorbs nutrients and water from the soil and anchors the plant. The functions of the root system are absorption, anchorage, conduction and storage. From the soil, roots absorb water, mineral salts, and oxygen. They anchor the plant firmly in place. They conduct water, mineral salts and sometimes foods, previously stored, to the stems and leaves above ground, and they conduct food from the leaves to all parts of the system underground. Most roots usually store foods at least for a short period and in small quantities, and special storage roots accumulate rather large amounts of food.

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