Secondary Growth in Plants
SECONDARY GROWTH IN PLANTS: Increase in width of the plant is considered as secondary growth. Secondary growth is seen in second year of plant growth. Secondary growth takes place in two steps. They are: 1.Cortical or Extra-stelar growth. 2. Stelar growth CORTICAL OR EXTRA-STELAR GROWTH: Formation of periderm: The cortex of the stem gets modified to meristem and acts as Cork cambium or Phellogen then it continuously divides towards outer side to form Cork tissue or Phellem and divides inner side to form Secondary cortex or Phelloderm The Phellogen, Phellem and Phelloderm together called as Periderm. Thus plants increase in its width. STELAR GROWTH: Formation of Intrafascicular cambium: The cambium which is present between xylem and phloem gets activated(able to divide) and forms Intrafascicular cambium. Formation of Interfascicular cambium: Medullary rays which is present between vascular bundles develops a cambium, that cambium is called I