Following cell division in root and shoot apical meristem cells, the growth could be arithmetic or geometrical. Growth may not be and generally is not sustained at a high rate throughout the life of cell/tissue/organ/organism. One can define three principal phases of growth – the lag, the log and the senescent phase.
When a cell loses the capacity to divide, it leads to differentiation. Differentiation results in the development of structures that are commensurate with the function the cells finally has to perform. General principles for differentiation for cells, tissues and organs are similar. A differentiated cell may dedifferentiate and then redifferentiate. Since differentiation in plants is open, the development could also be flexible, i.e., the development is the sum of growth and differentiation. Plant exhibit plasticity in development.