Roots can serve as storage houses for the food produced by the plant.
Root system consists of a primary root and secondary roots. The primary root originates in the radicle of the seedling.
During its growth it re–branches to form the lateral roots or secondary roots. Generally, two categories of root system are recognized. They are,
- Taproot system: The first root produced from a seed is called the radicle. In many dicotyledonous plants this root greatly enlarges to become the most prominent root of the plant and is known as a tap root (such as carrots, turnips, and sugar beets). The taproot gives rise to lateral roots, also called branch roots. The main function of the taproot is to store food.
- Fibrous root system or diffuse root system: In monocotyledonous plants, the radicle is short lived and does not give rise to a main root (such as turf grass). Instead, many small roots grow from the stem, with each small root forming its own lateral roots. The whole root system is fibrous and branches in all directions. The main function of the fibrous root is to anchor the plant.
Roots also act as the gatekeepers for the plant by actively regulating the entry of substances into the plant body
In most plants the absorption of water and minerals occurs primarily near the root tips with the aid of outgrowths called root hairs. Root hairs are small hair–like extensions of the outer layer of root epidermal cell (protective cell on a plant surface). Their function is to absorb nutrients and water. Roots can have an amazingly large number of root hairs. Root hairs increase the surface area of the roots, increasing the capacity to absorb nutrients and water. For example, a rye plant can have more than 14 billion root hairs that make up a surface area about as large as a football field.
Thus, the four major functions of roots are 1) absorption of water and inorganic nutrients, 2) anchoring of the plant body to the ground, and supporting it, 3) storage of food and nutrients, 4) vegetative reproduction.