<P> The vascular cambium is the main growth layer in the stems and roots of many plants , specifically in dicots such as buttercups and oak trees , and gymnosperms such as pine trees . It produces xylem on the inside and phloem on the outside . In herbaceous plants , it occurs in the vascular bundles which are often arranged like beads on a necklace forming an interrupted ring inside the stem . In woody plants , it forms a continuous ring and grows new wood on the inside . </P>
where do secondary xylem and phloem cells arise from
The vascular cambium