To keep pace with the expanding central stelar region during stelar growth, the pericycle with parenchyma or collenchyma cells acquire secondary meristematic property by de-differentiation and gets converted to phellogen or cork cambium. The epidermis gets ruptured and the newly formed periderm (secondary meristem) becomes the protective layer. Cork cambium is found in the vascular plants and is part of the periderm. This is a lateral meristem responsible for the secondary growth in roots and stems.