The part of a flowering plant above the ground is termed as the shoot system while the part below the ground is termed as the root system. The root system provides anchorage to the plant, synthesises plant growth regulators and absorbs water and minerals from the soil. A root has a root cap, a region of meristematic activity, a region of elongation and a region of maturation along with root hairs.
The root cap at the tip protects the root while entering the soil. The region of meristematic activity just above the root cap, rapidly divide to produce new cells for growth. The cells in the region of elongation rapidly enlarge and elongate the root. The region of maturation has elongated cells that differentiate and mature and develop root hairs. The root hairs assist in the absorption of water and minerals from the soil.
In dicotyledonous plants, the radicle grows into the soil to form the primary root, which further branches to form secondary and tertiary roots. The primary root along with its branches forms the tap root system. In monocotyledonous plants, the primary root is short lived and is replaced by a network of many large and small roots originating from the base of the stem, called the fibrous root system. In monstera and grass, the roots do not arise from the radicle, but emerge from the stem or the leaf, called adventitious roots.
The modified adventitious roots in sweet potato plants swell up and store food, while the modified adventitious roots in banyan trees, called the prop roots, support the tree. In sugarcane and maize, the stilt roots emerge from the lower node of the stem and support the plant. In rhizophora, which grow in swampy areas, modified roots called pneumatophores, absorb oxygen for respiration.