where do secondary xylem and phloem cells arise from
Vascular cambium
short
The vascular cambium
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 .