The rapidly dividing cells of the meristems which result in an increase in the number of cells in the plant, represent the meristematic phase of growth. The cells in this phase are in active state of metabolism.
Elongation phase involve increase in cell size due to increase in protoplasm, vacuolation and cell wall deposition.
In maturation phase cells attain maximum size, undergo maximum thickening of the cell wall to attain their final state. Most of the cells in a plant body are in the maturation phase.