How does Geotropism Work in Plants?

What is Geotropism?, How does geotropism work, Geotropism in Plants

In order that roots may always grow where they can best absorb food materials, they show a tendency always to grow downward, i.e., toward the earth. This might at first thought he credited to mere weight, but it is evident that stems, though equally heavy, cannot be made to grow down, and that roots, though lighter than the soil, still force their way through it, and cannot be made to grow upward, even though repeatedly started in that direction.

This turning of roots and stems is caused by the attraction of the earth, called gravitation, and this response that plants make to gravitation is called geotropism —positive in the case of roots, and negative in the case of stems. Positive geotropism plays an essential part in absorption by causing the roots to penetrate the soil rather than grow in any chance direction.