Theory:

Though there were plenty of plants in different colours and hues, they all have a few commonality among them.
 
Most of the plants have the following systems in common:
  1. Root system
  2. Shoot system
Plant.svg
The root system:
Roots are found under the ground at the base of the stem. Roots are 'positively geotropic' grow downwards responding to gravitational force. The following are the functions of the root system in plants:
  • Make the plant immobile and
  • Have a fixed position in the soil
  • Have more stability
  • Absorb soil nutrients and water
In some plants the roots also work like a store house of its excess food. For example: beet root, carrot, etc.
There are two major types of root:
  1. Tap roots
  2. Fibrous roots
 
Tap root system:
This system of root has a main root that grow vertically downwards tapering in to the soil and lateral roots that grow from the main root on the sides. These lateral roots further develop secondary and tertiary roots and rootlets.
Example:
Trees like mango and neem and herbs like soya beans.
 
Fibrous root system:
Fibrous root system grows at the base of the stem as a cluster of fibre.  They do not have an organization like tap root system.
Example:
Many monocotyledonous plants like grass, paddy, maize are found to have this type of root system.