Why Do Plants Have Roots?

A plant needs roots for two chief reasons: as a means of anchor­age or support, and to absorb water and mineral salts from the soil.

The roots of most plants grow in the soil. They don't "just sit there", but seem to reach out in the soil to help the plant grow. By elongating near their tips, roots are always coming in contact with new portions of soil.

Thousands of tiny root hairs project from the surface of the young root and absorb materials from the soil. That's why when a young root is pulled from the soil, soil particles often cling to the root hairs.

Some plants have taproots. A taproot is a large, single root, much larger than any of the branch roots. Other plants have not one large root, but several roots of approximately equal size. These form what is called a fibrous root system.

Grasses have fibrous root systems. Soil in which there are many fibrous roots is protected in this way from erosion. In other plants, most of the roots grow from stems as, for example, the geranium.

As roots grow older, some of them store large quantities of sugar and starch. Beet and sweet potatoes are examples of this. A sweet potato is a root, but an Irish potato, with its eycs, is a stem.

Not all plants have roots that grow in the soil. Some tropical orchids that grow on trees have spongy roots that grow in the air and absorb moisture. Both the English ivy and poison ivy cling to walls or trees by means of tiny aerial roots.

Some plants have special roots that develop from the stem above the ground and grow down into the soil, forming props. A few roots, such as the sweet potato, form buds that grow into leafy branches and can be used to the plant .