Root System

In most trees and wildflowers, one root, the taproot, is more prominent than the other fibrous roots. The taproot is usually relatively large in diameter and extends more deeply than the plant's other roots, and often has additional lateral roots.

Other plants, particularly grasses, have fibrous root systems formed from many roots of more or less equal size. In general, taproots extend more deeply than fibrous roots, with fibrous roots occupying a greater proportion of the upper soil layers.

Plants may also form other types of roots, such as buttress roots, which form large above-ground support structures such as the lower trunks of plants like the bald cypress and some fig trees. Buttress roots are especially useful in supporting these trees in moist soil. Prop roots arise either from the lower stem (as in corn) or from lower branches (as in red mangrove, banyan, and certain palms), and provide extra stability for these shallow-rooted plants. Climbing plants (such as ivy) produce roots that aid in attaching the plant to other plants, buildings, and walls. Other air roots, such as those found in mangroves, grow up out of the oxygen-deprived mud in which these plants typically grow and aid in the uptake of oxygen. This growth is unusual for roots, for these roots grow away from the force of gravity, rather than toward it. Perhaps the most unusual root system is that of the flower-pot plant, whose roots grow into a hollow structure formed from the plant's own modified leaves. This hollow structure collects rainwater, which the roots then absorb.