Living beings need energy to carry out various biological functions. This energy comes from food. 

Some important plants which provide food are as follows:

Cereals: Cereals are the most important food. Cereals come from plants of grass family (Graminae or Poaceae) and are the main source of starch. Starch is the main respiratory substrate in human body. Some cereals are as follows: wheat, rice, maize, millet, barley, etc.

Pulses: Pulses are the main source of protein for vegetarians Pulses belong the the Leguminoceae family of plants. Some examples of pulses are as follows: gram, red gram, pea, groundnut, etc.

Oil Yielding Plants: Vegetable oils are complex compounds of carbon which are made up of hydrocarbon, ester, alcohol, aldehyde, etc. Oils are of three types, viz. edible oils, inedible oils and aromatic oils from which edible oil is used in food. Examples are mustard oil, sunflower oil, etc.

Important Spices: Indian food is incomplete without spices. Different types of spices are used in Indian food, e.g. black pepper, cumin, red chilli, fenugreek, clove, cardamom, cinnamon, turmeric, garlic, ginger, star aniseed, etc.
Beverages: Tea and corfee are the most often used beverages around the world.

Vegetables: Vegetables are important part of a balanced diet. Vegetables are important sources of vitamins, minerals, fibre and water. Vegetables are obtained from different parts of plants, e.g. root, stem, leaves, flower and fruit.

Fruits: Fruit is a mature ovary which is formed after fertilization in flowering plants. Fruits are generally eaten raw. Jams, jellies, squash, etc. are made from fruits.