Secondary growth in plants

The length of the roots and stems in the plant are increased with the growth in the apical meristem. This type of growth is called as primary growth. Many of the dicot plants will show increase in the diameter of the trunk. This particular increase in size is known as secondary growth. The plant tissues that are participating in the secondary growth are the two lateral meristems called as cork cambium and vascular cambium.

The vascular tissues like xylem and phloem are separated from the cambial tissue, which is of meristematic in origin. This meristematic region is called as vascular cambium. In the case of young stem, vascular cambium is observed to be present as a single layer between the xylem and phloem. In the dicot stem, the cambial cells that are present between the xylem and phloem regions form a layer called intra-fascicular cambium. The medullary cells that are growing between the intra-fascicular cambial cells are transformed as meristematic and form inter-fascicular cambium. The intra-fascicular cambium and inter-fascicular cambium unite to form a cambial ring.