The majority of vascular plants consist of roots, shoots, and leaves. The root system penetrates the soil below ground and anchors the plant; there, the roots absorb water and various materials necessary for plant nutrition. The shoot system consists of the stem and the leaves and is the part of the plant above ground level. The stem provides the framework for the positioning of the leaves; the leaves are the sites of photosynthesis. Growing plants maintain a balance between the size of the root system and the shoot system. The total water- and mineral-absorbing surface area in young seedlings usually far exceeds the photosynthesizing surface area. As a plant ages, the root-to-shoot ratio decreases. Additionally, if the root system is damaged, shoot growth is reduced by lack of water, minerals, and root-produced hormones.