Parts of a Root and Their Functions
The root is commonly the underground part of the plant body. Unlike the stem, roots are distinctly characterized by the absence of nodes and internodes. Some plants with exception have their roots above the ground. These roots are called aerial roots because they help in gas exchange: Examples-Mangrove, Banyan, etc.
Origin and Development
The radicle is the first organ that forms after seed germination, which develops to form the primary or taproot. The primary root then further divides into branches to form the secondary root, tertiary root, and the root hairs – collectively called lateral roots.
What Are the Main Parts of a Plant Root System
A typical diagram of a root system broadly shows four distinct regions or zones, the i) region of root cap, ii) region of cell division or meristematic region iii) region of elongation, and iv) region of maturation or differentiation, with each region performing distinct functions to complete the root system in plants. Except for the root cap, the other three zones are collectively known as the ‘region of root tip’.
1) The Region of Root Cap
The tip of the root is protected by a multi-cellular (more than one cell) structure known as root cap. The cells in this region goes through constant division, renewing and growing in number as the root penetrates through the soil.
- Carrying water and minerals from the soil
- Protecting the sensitive growing tissues in the root
- Secreting the viscous mucilage-a 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, sack-like structure called root pocket, that does not have the protective functions and the cell renewing capability.
2) The Region of Cell Division (Meristematic Region)
Located a few millimeters above the root cap, the cells of the meristematic region are typically small, thin-walled, containing dense protoplasm. Meristematic cells contain three layers: i) Dermatogen – the outermost layer, ii) Plerome – the central region, and iii) Periblem – the innermost layer.
- Performing cell division to produce new cells for the root cap and basal region of the root
3) The Region of Elongation
Located next to the meristematic region, they are incapable of cell division.
- Performing growth and enlargement of the root cell that has lost the ability to reproduce.
- Helping in the absorption of water and minerals from the soil
4) The Region of Maturation or Differentiation
Also called the piliferous region, it is located next to the region of elongation. They develop when the cells of the elongation zone differentiate and mature into specialized tissues like root hairs, endodermis, cortex, etc.
- Keeping plants and trees anchored to the soil
- Forming specialized tissues like root hairs, xylem and phloem that help in absorption and transport of water and minerals from the soil
There are different types of roots, with specific types having some specialized functions, like storing foods, as well as the basic ones described above.
Article was last reviewed on Tuesday, January 14, 2020