What are The Kinds Of Roots?

The usual place from which roots develop is the lower end of the hypocotyl. Such roots are called normal roots. If they grow from other places such as the stem, leaves, or upper

part of the hypocotyl, they are called adventitious roots.

Normal Roots

Soil Roots

Of all forms of normal roots, the commonest are the soil roots and these are of many kinds, depending upon what functions they must perform and the character of the soil, moisture,

or climate that surrounds them. They in turn may be divided into three general classes.

Fibrous Roots are made up of many fine slender rootlets, giving large extent of surface for absorption. The roots of the grasses, for instance, are so numerous that they hold the soil together, forming a compact layer called the " turf."

Tap Roots are greatly enlarged primary roots which enable the plant to go deep after water supply and hold firmly in the ground. The thistle, dandelion, burdock, and many more of our worst weeds are thus adapted to make a living under adverse circumstances.

Fleshy Roots are adapted for storage of food stuffs and have the main part greatly thickened, as in the carrot, turnip, and beet. They are generally found in plants which require two seasons to mature their seed and so need stored food to carry them over the winter. In other cases, as the dahlia and sweet potato, the fleshy root is used to reproduce the plant.

Aerial Roots. Some tropical orchids which live attached to trees and never reach the earth at all develop aerial roots. They have a very thick, spongy cortex, which absorbs water from the moist air of the forests.

Aquatic Roots. These are found in a few floating plants such as the duck-wcted and water hyacinth. They are usually small, few in number, and lacking in root hairs. They do not need

extra surface for absorption because they are surrounded by an abundant water supply.

Adventitious Roots

Brace Roots

From the stems of corn and many other grasses, develop brace roots, which help to support the slender stems or to raise them again if they are bent down.

Roots for Propagation

In certain plants if the stem lies in contact with the soil for a sufficient length of time, roots will spring from the joints and produce new plants. The stems of various berry bushes can thus be fastened to the earth — " staked down " —and will take root in this way. The new root systems, when sufficiently developed, can be separated from the parent plant to make a new berry bush.

Slips or cuttings from certain plants develop adventitious roots from the stem or leaves and start new plants by this means. Many plants, like the strawberry, send out horizontal stems called " runners " from which adventitious roots develop and produce other individuals.

Climbing Roots

The stems of poison ivy, trumpet creeper, and some other vines grow climbing roots which act chiefly as means of support. These plants have ordinary soil roots, also, for the purpose of absorption.

Parasitic Roots

In a few plants, such as the dodder and mistletoe, parasitic roots develop from the stem, penetrate into the tissue of some other plant, and absorb food from their victim, often causing its death or serious injury. The dodder is parasitic upon clover, golden-rod, and other plants; the mistletoe usually grows upon the oak.