The body of an organism is composed of cells. Cell forms the structural and functional unit of an organism. In multicellular organisms, specific groups of cells are responsible for performing specific functions in the plant body. The cells collectively form the tissue. The tissue is defined as a group of similar or dissimilar cells having a common origin and performing a common function. The cells composing a tissue may be closely packed together without any intercellular space or may be loosely arranged with intercellular spaces. Parenchyma, sclerenchyma, xylem, etc., are the different types of plant tissues.

The type of tissue that is composed of immature cells and are always in a state of division and producing new daughter cells, continuously by active cell division is called meristem. The cells of this tissue look more or less round and compactly arranged without intercellular spaces. Cells are completely filled up with dense cytoplasm and a prominent nucleus. The activity of meristematic tissue leads to an increase in length, breadth and internodal distance.