The root is an axial, usually underground vegetative organ of higher vascular plants, which has unlimited growth in length and positive geotropism. The root fixes the plant in the soil and ensures the absorption and conduction of water with dissolved minerals to the stem and leaves.
1. The roots anchor the plant in the soil and hold it firmly throughout its life.
2. Through the roots, the plant receives from the soil water and minerals dissolved in it.
3. In the root of some plants, reserve substances can accumulate.
Types of roots
There are three types of roots: main, adventitious and lateral.
When the seed germinates, the embryonic root develops first. It becomes the main root.
The roots that form on the stems, and in some plants and on the leaves, are called adventitious.
Lateral roots extend from the main and adventitious roots.
Types of root systems
The roots of one plant in the soil form the root system.
There are 2 types of root systems:
1.The tap root system consists of one main root and many lateral roots.
Example: dandelion, sorrel, carrot, beet, etc. have such a root system.
2. The fibrous root system consists of adventitious and lateral roots of approximately the same size. The main root in plants with a fibrous system is insufficiently developed or dies off early.
Example: such a root system is found in wheat, barley, onion,
The root tip consists of small living cells of the educational tissue. The cells are constantly dividing here, so this section of the root is called the division zone.
The root tip is covered with a root cap like a thimble. The root cap is formed by cells of the integumentary tissue, which protect the delicate cells of the root division zone from damage by solid soil particles. These cells are short-lived, they gradually die off and slough off, and new ones are constantly being formed instead of the dead ones.
Under the cap is a growth cone, which consists of educational tissue. There is continuous cell division. This is the division zone.
Behind the division zone there is a growth (extension) zone. Here, the cells are stretched, as a result of which they grow in length.
Behind the growth zone is the suction zone, in which water and minerals are absorbed by the root hairs. The absorbed water and minerals move up the root along the conduction zone.
A root hair is an outgrowth of a root cell. The large number of root hairs increases the suction surface. Therefore, when transplanting plants, the roots must be protected and moved with the greatest possible amount of the surrounding soil.
Root hairs under an electron microscope. The root hairs are in direct contact with the soil and absorb water and minerals dissolved in it.