secondary xylem and phloem in dicot stems are produced by
Vascular cambium Other names for the vascular cambium are the main cambium, wood cambium, or bifacial cambium. In more detail, the vascular cambium is a plant tissue located between the xylem and the phloem in the stems and roots of certain vascular plants.[1]:125 It is a cylinder of unspecialized meristem cells that divide to form secondary vascular tissues. It is the source of both secondary xylem growth inwards towards the pith,[2] and secondary phloem growth outwards to the bark. Unlike the xylem and phloem, it does not transport water, minerals or food through the plant.[2]