Parts of a Root and Their Functions

The developing embryo or radicle is the first part to emerge from the seed during its germination, which later forms the primary root or taproot of the plant. The primary root then further divides to form the secondary root, tertiary root, and root hairs to complete the root system.

A typical plant root system shows four distinct regions or zones: 1) region of root cap, 2) region of cell division or meristematic region 3)  region of elongation, and 4) region of maturation or differentiation. Each region of the root performs specific functions. Except for the root cap, the other three zones are collectively known as the ‘region of root tip’.

The tip of the root is protected by a multi-cellular (more than one cell) structure called root cap. The cells of the root cap are always in a state of division, thus constantly renewing and growing in number as the root penetrates the soil.

Functions

• Carrying water and minerals from the soil
• Protecting the sensitive growing tissues in the root
• Secreting the viscous mucilage that helps the root to penetrate the soil
• Communicating with soil microorganisms

The root cap is absent in some aquatic and parasitic plants, where they are replaced by a more specialized structure called root pocket. They do not have the protective functions of a root cap and also the capability to divide.

It is located a few millimeters above the root cap. The cells of the meristematic region are typically small, thin-walled, and contain dense protoplasm. Meristematic cells contain three layers: i) Dermatogen – the outermost layer, ii) Plerome – the middle layer, and iii) Periblem – the innermost layer.

Functions

• Performing cell division to produce new cells for the developing root
• Helping in root elongation

It is located next to the meristematic region. They are incapable of cell division.

Functions

• Helping to increase the length and size of the root cell that has lost the ability to multiply.
• Helping in the absorption of water and minerals from the soil

Located next to the region of elongation, it is also called the piliferous region. They develop when the cells of the elongation zone differentiate and mature into specialized tissues such as root hairs, endodermis, and cortex.

Functions

• Keeping plants and trees attached to the soil
• Forming specialized tissues like root hairs, xylem, and phloem that helps in absorption and conduction of water and minerals from the soil