Vessels differentiate immediately beneath the vascular cambium in the late-formed xylem.
The outer ring of the stem contains all the functional tissue, including xylem, cambium , phloem, supporting tissues, and epidermis.
Vascular secondary growth results from the activity of the vascular cambium , which produces secondary phloem and secondary xylem.
Small blocks of tissue, including cambium and the adjacent phloem and xylem, were cut with a sharp knife and a chisel from the stem of a single specimen of K. pictus that was growing on the campus of Hokkaido University.
The cambium produces phloem tissue to the outside and xylem tissue to the inside.
A small block containing phloem, the cambial zone and two or three annual rings was punched out with a knife and chisel.
The first pattern is related to the differentiation of the cambial derivatives to either xylem or phloem through periclinal segmentations.
On well-aerated soils, transpiration may play a vital role in supplying oxygen to xylem and inner cambial zones during the growing season.
As revealed by light microscopy observations, the cambial region comprised the cambium, immature phloem, and immature xylem cells.
This layer is usually referred to as the ‘stripes of cell wall residues’ and originates from crushed cambial cells and cambial derivatives on both sides of the cambium.