Unlike animals, plants do not stop growing after reaching maturity. They continue to grow and bear new roots, leaves, branches, flowers, etc. While roots, stems and their branches have indefinite growth, other organs like leaves, flowers and fruits show limited or definite growth. They appear and fall off periodically and sometimes repeatedly. In lower plants, growth is diffused as every cell can divide and enlarge. Higher plants possess specific areas which take part in the formation of new cells. These areas are called meristems. Meristems are of three types- apical, intercalary and lateral. Cells of the meristematic region have the capacity to divide and self perpetuate. They produce cells which lose the capacity to divide and enter $G_0$ phase for undergoing differentiation to form particular tissues and organs. The meristem which is consumed in the formation of an organ is called determinate meristem. The meristem which continues its activity throughout life of the plant is called indeterminate meristem. It is the reason behind indefinite growth of plants.