Theory:

Earth is a green planet which is filled with many plants and animal species. In the world, a lot of diversity exists within the plants and animals. There are plenty of natural plant resources that are present around us.
 
earth-2923817_1280.jpg
The earth
 
Economic botany is a field of science that focuses on how the plants can be useful for the people. It primarily deals with how plants are useful for the human welfare - as food, clothing, shelter and medicine which are used directly or indirectly.
 
2048px-Elements-of-biodiversity.png
Diversity in living organisms
  
Indirect usage includes the needs of mans livestock and the maintenance of the environment. The direct benefits may be commercial, domestic, environmental, or also can be aesthetic.
Plants are useful for the country's economy to a great extent. It is also noted that a country's wealth depends mostly upon the agriculture and plant products.
Economic botany is the study of relationship between people and plants and the usefulness of plants in the economy.
Rice, wheat, and millets have been the staple foods of the Indian population seen in the ancient times. Evidences include the presence of charred grains in the excavation sites. In addition, abundant information is available in ancient literature about the existence and usage of several crops that are of economic importance.
Uses of plants to human:
Plants provide oxygen (\(O_2\)) through the process of photosynthesis that are used for respiration by humans and other animals.
 
Plants are great contributors to the economy of a nation.
Economic plants are plants that can be utilised directly (in food) or indirectly (products that can be used or which enhance the environment) for humans benefit.
Observe the pictures given below:
 
 (1)_Agriculture_and_rural_farms_of_India.jpg
Harvesting of paddy by farmers
  
Important!
Indians consume rice as food.
Women_at_work_in_a_small_scale_coir_spinning_unit_at_kollam.jpg
Women making rope using coir
  
Important!
The rope is made from fibres of plants including hemp, jute or flax.
neem-leaves-651913_1280.jpg
Neem leaves
 
Important!
Neem leaves are used for medicinal purposes as well as pesticides or insecticides.
 37158925023_d61ffca735_c.jpg
Using the wood (obtained from plants) to make wooden products
 
In this chapter, the different crop plants and its usefulness in the economy are discussed.
Reference:
https://commons.wikimedia.org/wiki/File:Elements-of-biodiversity.png
https://upload.wikimedia.org/wikipedia/commons/thumb/b/be/Women_at_work_in_a_small_scale_coir_spinning_unit_at_kollam.jpg/512px-Women_at_work_in_a_small_scale_coir_spinning_unit_at_kollam.jpg
https://upload.wikimedia.org/wikipedia/commons/f/f1/%281%29_Agriculture_and_rural_farms_of_India.jpg
https://www.flickr.com/photos/cifor/37158925023