G ROWTH Growth is regarded as one of the most fundamental and conspicuous characteristics of a living being. What is growth? Growth can be defined as an irreversible permanent increase in size of an organ or its parts or even of an individual cell. Generally, growth is accompanied by metabolic processes (both anabolic and catabolic), that occur at the expense of energy.
Therefore, for example, expansion of a leaf is growth. How would you describe the swelling of piece of wood when placed in water? . .
Plant Growth Generally is Indeterminate Plant growth is unique because plants retain the capacity for unlimited growth throughout their life. This ability of the plants is due to the presence of meristems at certain locations in their body. The cells of such meristems have the capacity to divide and self-perpetuate. The product, however, soon loses the capacity to divide and such cells make up the plant body.
This form of growth wherein new cells are always being added to the plant body by the activity of the meristem is called the open form of growth. What would happen if the meristem ceases to divide? Does this ever happen? In earlier classes, you have studied about the root apical meristem and the shoot apical meristem.
You know that they are responsible for Seed coat Epicotyl hook Cotyledons Cotyledon Soil line Epicotyl Hypocotyl Hypocotyl Figure . Germination and seedling development in bean the primary growth of the plants and principally contribute to the elongation of the plants along their axis. You also know that in dicotyledonous plants and gymnosperms, the lateral meristems, vascular cambium and cork-cambium appear later in life. These are the meristems that cause the increase in the girth of the organs in which they are active.
This is known as secondary growth of the plant (see Figure . ). . .
Growth is Measurable Growth, at a cellular level, is principally a consequence of increase in the amount of protoplasm. Since increase in protoplasm is difficult to measure directly, one generally measures some quantity which is more or less proportional to it. Growth is,