Roots

Roots are commonly understood to anchor the plant and take up water from the soil. The latter portion of this description leads to an equally common misunderstanding that roots seek water. It is easy to devise a demonstration that dispels this idea. First, place a layer of moist soil in a pot and top this layer with a layer of dry soil followed by another layer of moist soil. Next, plant a seed in the uppermost layer of moist soil. When the seed germinates, the root will grow downward until it makes contact with the dry soil, where it will stop. It cannot, of course, grow through the dry soil in order to reach the moist soil below. The principle is easy to follow “roots grow where they can grow.” It might be called the principle of the self-evident.