Vascular cambium: The vascular cambium is a ring of meristematic tissue; it is responsible for the secondary thickening in the dicot plants. It is formed by the interconnected fascicular cambium and inter fascicular cambium and forms a ring of cambium. This vascular cambium gives rise to secondary xylem towards the inner side and secondary phloem towards the outer side.
Cork cambium: The cork cambium is formed of secondary lateral meristem since it arises from the any of the permanent cells. Due to the continued secondary growth the secondary tissue formed will exert pressure on the epidermis and as a result it ruptures. At this stage the cork cambium will be formed from the permanent cell and become active. The Phellogen or the cork cambium starts its activity and produces the phelloderm towards inner side of cork cambium. Phellem or cork is formed towards the outer side the secondary cortex, cork and cork cambium all together known as periderm. The main function of the periderm is the protection of tissue.