Types of Roots
The root is the most important part of a plant that grows down to the soil and water. It is mainly responsible for anchoring the plant to the ground and absorbing the nutrients and water from the soil.
There are different types of roots depending upon the shapes, size, and species of plants.
The major types of roots are:
- Tap Root
- Fibrous Root
- Adventitious Root
Tap Root System
Do you know where the root originates from? There is a part at the bottom of the seed called a RADICLE, from which the root growth begins.
When a seed germinates, a single root originates from the radicle that grows vertically down into the soil. This is called the primary root or tap root. A taproot system penetrates deep into the soil.
The roots which grow directly from the primary root are called lateral roots or secondary roots. There are many tiny hairlike structures on the root, known as the ROOTLETS or ROOT HAIR.
This arrangement of root is called a Tap Root System. Taproot provides a very strong anchorage to the plant.
Characteristics of Tap Root:
- It develops directly from the radicle and grows vertically downwards.
- Only one main root that grows from the end of the stem is called the primary root.
- The primary root gives out branches of secondary and tertiary roots.
- The lateral roots of the taproot are called secondary and tertiary roots.
- It is very thick, straight, and goes deep into the soil.
- Very fine hairlike structures on the root, known as the rootlets or root hair.
- There is a root cap on the tip of the root that protects the root cap.
Examples of Tap roots: bean, hibiscus, mustard, carrot, beetroot, parsley, china rose, etc.
Fibrous Roots System
In a fibrous root system, the primary root is short-lived and is replaced by a bunch of thin fiber-like roots. These fiber-like roots are produced from the base of the stem. These are called fibrous roots.
In this type of root system, roots do not originate from the radicle. These roots spread from a common point and are about the same size.
There is no difference between the main roots and branch roots. They spread out in the soil and give firm support to the plants.
Characteristics of Fibrous Root:
- A fibrous root system is the opposite of a taproot system.
- It does not originate from the radicle of a seed.
- Fibrous roots are produced from the base of the stem.
- The primary root is short-lived. Numerous roots replace it, also called adventitious roots.
- They do not penetrate deep into the soil.
Examples of fibrous roots: Rice, wheat, maize, marigold, banana, grasses, etc.
Adventitious Roots System
Adventitious roots are very similar to fibrous roots. Roots forming from other parts of the plant except radicle are called adventitious roots. They can grow underground or aerial. An aerial root grows above the ground and absorbs nourishment directly from the air.
Usually, adventitious roots may originate from any nodes, internodes, stem or the branch or even from the leaf.
Examples of adventitious root: orchids, banyan tree, mangroves etc.
Adventitious roots can be further subdivided into different categories based on the location and shape of the swollen parts.
➤ Tuberous Roots: e.g. sweet potato
➤ Fasciculated Fleshy Roots: e.g. dahlia
➤ Palmate Roots: e.g. orchid
➤ Nodulose Roots: e.g. turmeric
➤ Beaded Roots: e.g. Indian spinach
➤ Prop Roots: e.g. banyan tree
➤ Stilt Roots: e.g. sugarcane
➤ Buttress Roots: e.g. salmalia
➤ Climbing Roots: e.g. betel wine
➤ Floating Roots: e.g. jussiaea
➤ Clinging Roots: e.g. orchids
➤ Reproductive Roots: e.g. Sweet potato, Dahlia
Functions of Roots
Anchoring and supporting the plant: Root anchor the plant firmly in the soil.
Absorption and Conduction: The roots absorb water and nutrients from the soil in mineral solution through the root hairs. The root hairs absorb the nutrients and conduct them to the shoot system via xylem through capillary action.
Transportation: Absorbed water and minerals from the soil are transported to the shoot system through the root.
Holding the soil together: Roots help to hold the soil together. This prevents washing away of the soil by wind or water.
Storage: Some roots are modified for the storage of food. e.g., radish, carrot, etc
Extra or Mechanical Support: In some plants, the roots support heavy horizontal branches. In Banyan, maize, sugarcane, bombax, etc., the roots protect the shoot from falling.
Photosynthesis: Root plays a crucial role in the process of photosynthesis. Leaves need water, CO2, and sunlight to perform photosynthesis. They get water from the root system and release excessive water through the process of transpiration. At the time when the water vapors release out of the stomata through tiny pores, CO2 enters.