Meristematic Tissue

A meristem is a form of plant tissue that can be found in the stem. It is made up of undifferentiated cells (meristematic cells), which are capable of cell division and proliferation. Cells in the meristem have the potential to develop into any of the various tissues and organs found in plants. After a period of differentiation, these cells cease to divide and lose their ability to proliferate altogether. Plant cells that have been differentiated are often unable to divide or create cells of a different type. Meristematic cells are cells that have not differentiated or have only partially differentiated. They have the ability to divide indefinitely since they are totipotent. The division of meristematic cells produces new cells that are used for the expansion and differentiation of tissues as well as the initiation of new organs, resulting in the formation of the basic structure of the plant’s structure. The cells are tiny, with no or only a few vacuoles, and protoplasm completely fills the interior of the cell. They are undifferentiated, but they are present in a rudimentary form, and they are called chloroplasts or chromoplasts (proplastids). Meristematic cells are tightly packed together with no intercellular gaps between them. The cell wall is made up of a primary cell wall that is extremely thin. Apical (at the tips), intercalary or basal (in the middle), and lateral (at the sides) meristematic tissues are the three types of meristematic tissues (at the sides). At the meristem summit, there is a small collection of cells that are slowly dividing, which is referred to as the core zone by scientists. The cells in this zone have a stem cell function and are required for the maintenance of the meristem. Most of the time, the proliferation and growth rates at the meristem summit are significantly different from those at the periphery.

Types of meristems

A plant has four types of meristems: the apical meristem and three types of lateral meristems: the vascular cambium, the cork cambium, and the intercalary meristem. The apical meristem is the most prominent.

Apical meristems

These are found at the tips of roots and shoots, which are at the opposing ends of the plant’s axis. Cell divisions and subsequent cellular growth in these places result in the lengthening of the plant’s above- and below-ground portions. Because the patterns for the following growth are laid down in the meristems, the meristems have an impact on the forms of the mature plants as well.

Lateral meristems

Cambium vasculare (vascular cambium). A cylinder of tissue known as the vascular cambium, which extends across the length of the plant, from the tips of the shoots to the tips of the roots, allows some plants to increase in diameter by creating new tissues laterally from the centre of the plant. It can be found in all perennial plants as well as in some annual species. Secondary tissues are tissues that are formed as a result of cell divisions in the vascular cambium.

Cork cambium is a kind of cork. Cork cambia, also known as phellogens, are located in the bark of the roots and stems of woody plants, where they generate cork cells. They are found in the bark of the roots and stems of woody plants. Some tree species have lengthy cylinders of cork cambia that run parallel to the vascular cambium. The cork cambia starts just beneath the epidermis of the primary body and is found in some tree species. On the other hand, more distinct, disk-like cork cambia in the trunks of other species result in flat plates of bark tissues that break off on huge scales as the tree becomes older.

An intercalary meristem is a meristem that occurs between two periods of time. Plants with intercalary meristems are found along the stems, at the nodes, of grasses. The stem is being pushed higher by cell divisions in this tissue. The absence of lateral meristems in grasses and other monocots means that any lateral growth in size is the product of primary tissue cell elongation, rather than cell division.

Primary (transitional) meristems

It is immediately apparent that the cells produced by divisions in the apical meristem region are divided into three zones of separate tissues that differentiate below the level of the apical meristem. The protoderm, the procambium, and the ground meristem are the primary meristems, which are also referred to as transitional meristems in some instances. They are responsible for the formation of the tissue systems of the basic plant body.

Meristematic Tissue On the basis of the country of origin

Promeristem

• The meristematic tissue is the most primitive and the most recent.
• It is derived from the embryonic stage.
• The promeristem is the meristem that gives rise to the primary meristem.
• It can be found in the base and the tips of the shoots.

Primary Meristem

• The promeristem is the source of this phenotype.
• Cells divide on a regular basis.
• It is found below the promeristem and is responsible for the formation of permanent tissue.

Secondary Meristem 

• Its origins can be traced back to the main meristem.
• The secondary meristem is responsible for the formation of permanent tissue.

Characteristics of Meristematic Tissue

The following properties of meristematic tissue can be observed:

• Meristems are a term used to describe the cells that make up these tissues.
• The meristematic tissue has the ability to regenerate on its own. Every time a cell divides, one cell retains its identity as the parent cell, while the other cells develop specialised structures of their own.
• They have a modest number of vacuoles and are quite small.
• The meristematic tissue is alive and has a thin-walled structure.
• The protoplasm of the cells contains a great deal of information.
• The meristematic tissues of a wounded plant repair the damage done to it.
• The cells of the meristematic tissue are immature and in their early stages of development.
• They do not keep food on hand.
• They have a tremendous amount of metabolic activity.
• They are characterised by a single, big, and conspicuous nucleus.

Conclusion

Meristem tissue gives birth to more dermal, ground, and vascular tissue, as well as to more of its own tissue and organs. Apical meristems are responsible for the formation of primary tissues. Cells next to the apical meristem are the first to divide. Then they become longer, and finally, they become more distinct. Primary meristematic tissue aids in the growth of the plant’s length or vertical growth, which means that it aids in the growth of the plant up toward the sun and down into the earth. Secondary meristematic tissue aids in the expansion of the girth or lateral growth of a plant’s stems, branches, and roots, among other things.