Physiological aspects of wood formation.

Functionally the stem of a tree consists of three tissues - the phloem, the vascular cambium and xylem. The phloem and xylem arise from the vascular cambium. The cambium forms a complete sheath in the tree covering the xylem from the root tips to the tips of the twigs. Each Spring when the cambium becomes active it starts to divide and splits off both new phloem and new xylem mother cells. These cells then pass through a process of differentiation, elongation and maturation before they are recognisable as xylem and phloem cells...