The
vascular cambium (plural
cambia) is a plant tissue located between the
xylem and the
phloem in the stem and root of a vascular plant, and is the source of both the secondary xylem growth (inwards, towards the pith [material at the center of plant, often dead and/or deteriorated, that is composed of parenchyma tissue]) and the secondary phloem growth (outwards [to the bark, rough or smooth, of the plant]). It is a cylinder of unspecialized
meristem cells that divide to give new cells which then specialize to form
secondary vascular tissues.