The root system of a flowering plant begins its development from the hypocotyl of the embryo of the seed which gives rise to the primary root. Roots generally grow downwards into the soil (positively geotropic) and upwards (negatively geotropic). Roots do not bear leaves and therefore no nodes are present.Two kinds of root systems can be distinguished in flowering plants: tap root systems and adventitious root systems. Usually dicotyledons posses tap root systems and monocotyledons adventitious root systems.
Tap Root System: The primary root grows vertically down into the soil in the tap root system. Later lateral or secondary roots grow from this at an acute angle outwards and downwards, and from these other branches may arise. The main or primary root is known as the tap root; together with itsmany branch roots it forms a tap root system e.g. the bean.
Adventitious Root System: The primary root usually dies at an early stage and is replaced by numerous roots that develop from the stem. These roots, which develop from the stem, are equal in size. They are known as a adventitious roots, which give rise to branch or lateral roots and form anadventitious root system, e.g. the mealie.
Functions of the Root
Roots anchor the plant in the soil.
Roots absorb water and mineral salts from the soil.
Roots may store food.
Roots form a passage way for water and dissolved substances from the root into the stem and also for foods from the stem down into the root.
Root of a Dicotyledonous Plant: External Features
If we study the root tip of a flower plant under a dissecting microscope or with a hand lens, the following regions can be distinguished:
The Root Cap
The tip of the root is covered by a cap that is shaped like a thimble. The outer cells of the root cap are continuously being worn away and new cells are added to the inner portion. As these cells disintegrate they form a strong protective cover.
Function
The root cap covers and protects the delicate