The part, or organ, of the plant or grass that typically grows below the surface of the soil. Roots that grow above ground are known as aerial. A root that grows below ground lacks nodes, or connecting joints, and has no leaves. A root primarily absorbs water and nutrients and anchors the body of the plant to the ground. Maintaining a good root structure in a lawn is very important. Proper lawn and grass care should be practiced in order to continue to help preserve good root structure and support plant, tree, or grass growth.