The Root

• The primary root are designed by the direct elongation of the radicle and develops inside the soil, in mainstream of the dicotyledonous plants. The primary root has numerous orders of lateral roots and these are termed as secondary, tertiary, etc. roots.

Different types of roots are:

· Tap roots

· Fibrous roots

· Adventitious roots

Tap root:

The primary root with its branches form the tap root system. Ex., Mustard plants.

Tap roots

Fibrous Root:

The primary root are short lived in monocotyledonous plants and it is replaced by a large number of roots, which originate from the base of the stem and constitute the fibrous root system. Ex., Wheat plants.

Adventitious Root:

In some other plants like grass, Monstera and the banyan tree, the roots are found arising from parts of the plants other than the radicle and it is termed as adventitious roots.

• The role of roots are to absorb water and minerals from the soil, providing a proper waterfront to the plant parts, storage of reserve food materials and amalgamation of plant growth regulators.

Regions of the Root:

The regions of the root-tip

• The root is covered at the apex by a protector like structure called root cap, which protects the tender apex of the root as it penetrates through the soil. The area above the root cap is the region of meristematic activity. 

• The cells in this region divide constantly, they are small, thin walled and with solid protoplasm. The cells adjacent to this region experience speedy elongation and increase and are the prime cause for the growth of root length. This specific region is called as region of elongation. 

• The cells in this zone slowly distinguish and develop and this region is region of maturation.

• Some of the epidermal cells in this region form very fine, delicate thread like assemblies called, root hairs, which absorbs water and minerals from the soil.

Modifications of Root:

• The roots of some plants changes their shape and structures to suit themselves to perform functions like support, storage of food and respiration. Ex., Tap roots of carrot, turnip and adventitious roots of sweet potato, get enlarged and store food.

Modification of root for storage

• Those hanging structures that support a banyan tree are termed as prop roots. Supporting roots arising from the lower nodes of the stem are stilt roots. Ex., stems of maize and sugarcane. 

• In some plants growing in swampy areas, many roots comes out of the ground and grows vertically up and these are Pneumatophores assists to get oxygen for respiration. Ex., Rhizophora.

Modification of root for respiration: pneumatophore in Rhizophora