In the stelar region, secondary growth occurs by the activity of vascular cambium.A strip of cambium that originates from the procambium is present between the xylem and phloem of the vascular bundle. This cambial strip is called fascicular cambium. At the onset of secondary growth additional strips of cambium are formed from the interfascicular parenchyma between the vascular bundles.These later formed strips of cambium is known as interfascicular carnbium. These strips join with fascicular cambium and form a complete ring of cambium.