Thus, meristems are the region of active growth in plants. They are mainly found in the shoot and root apices that give rise to new organs and allow plants to grow and repair worn-out tissues. In 1858, Carl Wilhelm von Nägeli coined the term ‘meristem’. The term ‘meristem’ originated from the Greek word ‘merizein’, meaning ‘to divide.’
Characteristics of Meristematic Tissue in Plants
Functions of Meristematic Tissue
Types of Meristematic Tissue with Functions
Difference between Meristematic Tissue and Permanent Tissue
Can self-renew and self-sustain indefinitely. When meristems divide by mitosis, the cell that remains in the meristem is called an initial, and the other is the derivative. As new cells add up by repeated divisions of the initial cells, the derivative cells gets pushed away from the zone of active division. As they mature, the derivatives differentiate into other types of tissues.They are small and cuboidal in shape.Have a single, large, and prominent nucleusContain small vacuoles, thin cell walls, and dense cytoplasm.Have a high metabolic rate.Cannot store food
Allowing plants to grow vertically in lengthAllowing plants to grow in diameter, increasing the girth of the plantRepairing and regenerating damaged parts
1. Apical Meristem
This meristem is located at the tip of the root and stem. The cells produced by divisions in the apical meristem are divided into two types. The promeristem zone contains actively dividing cells (apical initials), and the meristematic zone consists of protoderm, procambium, and ground meristem. It is responsible for the primary growth of plants. It allows the plant to grow vertically in height, both above and below the ground, by extending the root and shoot tip.
2. Intercalary Meristem
It is found at the internodes or stem regions between the places where leaves attach. The intercalary meristem is seen in monocotyledonous plants, such as grass and pine. It also adds to the height of plants by increasing the length of the internode.
3. Lateral Meristem
This type of meristem is present on the lateral side of the stem and root of a plant. It increases the girth and thickness of the plant. The two types of lateral meristems are:
Vascular Cambium: Plants that grow in diameter add new tissues laterally in the form of cylinder called vascular cambium. It extends throughout the plant length from the shoot tip to the root tip. Tissues formed by division of vascular cambium are secondary tissues. Vascular cambium is mainly found in perennial plants and rarely in annual plants.Cork Cambium: Also called phellogens, are found in the bark of roots and stems of woody plants, producing the cork cells. They form under the epidermis and are long cylinders parallel to the vascular cambium. In other species, disk-like cork cambia produce flat pieces of bark tissues that fall off as the tree becomes old.
