On the basis of life span, plants are broadly divided into three groups :
1. Annual plants : Plants that have life span of one year or one season are called annual plants.
For example: maize, sorghum, millet, mustard etc.
2. Biennial plants : Plants which generally have a life span of two years are called biennial plants.
For example : Onion, Cabbage, Carrot etc.
3. Perennial plants : These plants live for more than two years and produce wood. These plants usually flower in summer or spring season. Perennial plants are usually large and shady trees.
For example : Neem, pine, banyan etc.
