Annual rings

The meristematic tissue in the plant stems and plant roots is called as cambium. The cross-sectionof stem in the plants commonly shows an outer covering called epidermis, cortex region followed by stele. The stele is surrounded by endodermis followed by pericycle and vascular bundles towards inside. There is a pith region made up of parenchyma cells in the center. As the plant grows, the tissues in the plant also grow. The production of new vascular tissues initially is classified under primary growth. If the vascular cambium grows further as a vascular ring and starts generating secondary xylem towards inside and secondary phloem towards outside of cambial ring, then the growth is described as secondary growth. The recently formed tissues lie nearer to the cambium while the matured tissues move away from the center. As the plant ages, based on the age of plant the formation of that many vascular rings will be seen with the secondary tissues derived from them. These vascular rings representing each year of the plant age are called as annual rings.