The vascular bundles are many in number, arranged in the form of a ring surrounding central pith. Each vascular bundle is conjoint (xylem and phloem combining to form a single bundle), cololateral (xylem and pholem on the same radius with x/p arrangement), open (open to secondary growth i.e., cabium is present) with endarch (protoxylem pointing towards the pith) xylem. Phloem consists of seive tubes companion cells and phloem parenchyma. In between phloem and xylem is present cambium which is said to be intrafascicular (present within a vascular bundle).
The canlbial cells are thin walled, rectangular and actively dividing. Next to the cambium, internally is the xylem, with the protoxylem facing the pith? Xylem consists of vessels, trachieds, wood fibres and xylem parenchyma. Between the vessels are found the wood parenchyma.