CBSE Class 9 Answered

Weeds are the plants which have their undesirable effects on the environment and economy. They compete with other plants for the resources and prohibit their growth.

Types of weeds:

Based on the life span there are three types of weeds.

• Annual type – These weeds complete their life cycle in the span of one year.

• Biennial type – These weeds have the life cycle that lasts of two years.

• Perennial type – These weeds have the life span which for more than two years.