Continuous state of dividing tissues called meristem. In connection to this, what is the role of lateral meristem?

Explanation

The secondary growth in dicots and gymnosperms is brougth about by two leteral meristems.
Vascular cambium and
Cork cambium
Vascular cambium
It is the lateral meristem that produces the secondary vascular tissue. i.e., secondary xylem and secondary phloem .
Origin and formation of Vascular cambium
(i) A strip of vascular cambium that is believed to originate from the procambium is present between xylem and phloem of the vascular bundle. This cambial strip is know as intrafascicular or fascicular cambium.
(ii) In between the vascular bundles a few parenchymatous cells of the medullary rays that are in line with the fascicular cambium become meristematic and form strips of vascular cambium. It is called interfascicular cambium.
(iii) This interfascicular cambium joins with the interfascicular cambium on both sides to form a continuous ring . it is called a vascular cambial ring.
Organization of Vascular cambium
(i) The active vascular cambium possesses cells with large central vacuole (or vacuoles ) surrounded by a thin layers of dense cytoplasm.
The most important character of the vascular cambium is the presence of two kinds of initials , namely fusiform initials are ray initials.
Fusiform initials
(i) These are vertically elongated cells. They give rise to the longitudinal or axial system of the secondary xylem (tracheary elements, fibers, and axial parenchyma ) and phloem (sieve elements, fibers and axial parenchyma).
(ii) Based on the arrangement of the fusiform initials, two types of vascular cambium are recognized.
Storied (stratified cambium) and non-storied
(Non-stratified cambium):
Storied (stratified cambium ):
If the fusiform initials are arranged in horizontal tiers, with the end of the cells of one tier appearing at approximately the same level , as seen in tangential longitudinal section (TLS), it is called storied (Stratified) cambium. It is the characteristic of the plants with short fusiform initials .
Non-storied (Non-stratified cambium) :
(i) In plants with long fusiform intials, they strongly
(ii) overlap at the ends, and this type of cambium is called non-storied (Non-stratified) cambium.
Ray intials
(i) Horizontally elongated cells.
(ii) They give rise to the ray cells and form the elements of the system of secondary xylem and phloem.
Activity of Vascular Cambium
(i) The vascular cambial ring , when active cuts off new cells both towards the inner and outer side.
(ii) The cells which are produced outward form secondary phloem and inward secondary xylem.
(iii) Due to the continued formation of secondary xylem and phloem through vascular cambial activity, both the primary xylem and phloem get gradually crushed.
Phellogen (Cork Cambium)
(i) It is secondary lateral meristem.
(ii) It comprises homogenous meristematic cells unlike vascular cambium.
(iii) it arises from epidrmis ,cortex, phloem of pericycle (extrastelar in origin).
(iv) its cells divide periclinally and produce radially arranged files of cells.
(v) The cells towards the outer side differentiate into phellem (cork) and those towards the inside as phelloderm (secondary cortex).