The meristematic cells of the vascular cambium are highly vacuolated and exist in two forms 1. Fusiform initials - vertically elongated 2. Periclinal divisions result in the formation of two cells, one in front or behind the other a. Secondary xylem and phloem are produced through periclinal divisions of the vascular cambium and their derivatives, i.e. the cell plate that forms between the dividing initials is parallel to the surface of the root or stem b. Those divided off towards the inside become xylem cells and those to the outside become phloem cells 2.
Anticlinal divisions result in the formation of two cells, side by side.
As the vascular cambium adds cells to the secondary xylem and the core of the xylem increases in width the cambium is displaced outward. In stems that undergo secondary growth the procambium between the primary xylem and primary phloem retains the ability to divide. Much more secondary xylem than secondary phloem is added 1. As the vascular cambium moves outward the primary phloem is pushed outward and crushed. With the initiation of secondary growth a periderm will form and it will replace the epidermis 1.