Meristematic tissue is a group of similar cells that are in a continuous state of division or retain their power of active cell division. , it is found at the effects of root, shoots, stem, branches, buds, etc. Meristematic Tissues or meristem include living cells having different shapes and sizes. Their main job is to possess a huge nucleus lacking vacuole. There is no cellular space between the cells and the area where these cells survive is called meristem.
Meristematic cells are immature plant cells that have the ability to divide themselves continuously through their lifecycle.Definition of Meristematic Tissue
Meristematic cells are generally tiny and spherical in shape. These cells have thick cytoplasm and comparatively fewer small vacuoles known as watery saclike enclosers. These cells are known as initials and balance the meristem as an ongoing source of newly born cells. These cells go through the mitosis cell division process many times before conversion into a particular cell needed for that area of the plant body.
Features of Meristem or Meristematic Tissue
The characteristics features of a cell of Meristem are as follows of
- Meristems are immature for young cells which have active power of cell division.
- Cells are isodiametric oval, rounded or polygonal in shape without intercellular spaces.
- The cell wall is usually thin and elastic which is made up of cellulose. The secondary cell wall is absent.
- Each cell possesses dense cytoplasm and a single distinct central nucleus.
- The central vacuole is absent except cambial cells and secondary meristem.
- Cell inclusions and reserve food material are absent.
- Metabolic activities are very high rate due to the high rate of respiration.
- There is a presence of collarless proplastids (eoplast) instead of the chloroplast.
You will have a better understanding of the Meristematic Tissue from this video.
Types of Meristem
Meristem or meristematic tissue is classified into different types on the basis of the following features:
A. On the basis of plane of cell division
1. Mass Meristem
It is a type of Meristem in which cells divide into our planes and increase the volume of plants. It is responsible for forming the formation of the early growth of embryos, sporangia, endosperm, etc
2. Plate Meristem
It is a type of Meristem in which cells divide into two planes and increase the area of the plant. It generally helps in the formation of flood areas like a leaf, lamina, epidermis, endodermis, pericycle, etc.
3. Rib Meristem
It is a type of Meristem in which cells divide anticlinal in a single plane only and increase the length of the plant. It is responsible for the formation of lateral roots, the formation of pith and cortex in the young stem.
Rib Meristem is also called file Meristem or radical meristem.
B. On the basis of their mode of origin
Meristem is following three types on the basis of origin
1. Promeristem (Primardial Meristem)
It is a group of earliest youngest meristematic cells in a growing region. They are present on the tip of the stem and root. Plant embryos truly represent this kind of meristem. They give rise to primary meristem.
2. Primary Meristem
It is a type of Meristem which is derived from the embryo. It originates from Promeristem. These cells are always inactive states of division and give rise to primary permanent tissues. They are present below the promeristem at the shoot and root apices, at the apex of leaves, and in the intercalary part. It gives rise to secondary meristem. Depending on the position, the primary meristem is three types:
- Apical Meristem
Apical Meristem is present at the tip or effects of steam, bud, root, and leaf. It increases the length of the plant.
- Intercalary Meristem
It is from the Apical Meristem which has been separated from 8 by the formation of permanent tissue in between apical Meristem. It helps in the elongation of plant parts. It also allows the fallen is steam of cereals to become erect. It is fully used in the formation of permanent tissue. It is commonly found at the bases of leaves or at the basis of internodes.
- Lateral Meristem
It is present along the sides of a stream which consists of a single layer of rectangular cells. These cells divide and increased the thickness of the girth of the plant. Intrafascicuar cambium present in steam is an example of this meristem.
3. Secondary Meristem
Secondary Meristem is formed from the permanent tissue by dedifferentiation. The common examples are vascular cambium of duct root, interfascicular cambium, and cork cambium of the dicot stem. They are not present from the very beginning of the formation of an organ but developed at a later stage.
C. On the basis of function
1. Protoderm (Dermatogen)
They are outermost meristematic cells. They give rise to the epidermis of the development of organs.
2. Procambium or Plerome
They are the innermost meristematic cells. They give rise to the primary vascular tissue (Primary xylem, Primary Pholem, and cambium) by elongation and differentiation.
3. Ground meristem or Periblem
It is the group of cells that gives rise to the hypodermis, cortex, endodermis, pericycle, pith, and medullary rays.
Functions of Meristem
- Meristem helps in the formation of new cells in various regions of the plant.
- The Apical Meristem of steam produces new leaves and branches.
- Reproductive shoot Apex forms flowers.
- Intercalary Meristem increases the length of internodes and protects the plant from loading.
- Root app is continuously added root hairs.
- Vascular cambium adds new vascular disease because the older ones become non-functional.
- Cork cambium forms cork cell to the outer side and secondary cortex towards the inner side of the stem and root.
- Lateral Meristem helps in secondary growth.
- Procambium letterforms vascular tissue.
- Ground Meristem later forms ground tissues.
- Protoderm later gives rise to the epidermis in the stem. In dicot root, it later gives rise to epiblema and root cap but in monocot root, it later gives rise to only epiblema.
- Dermatogen Gamla banana services may not be listed forms epidermis in stem and epiblema in the root.
- Peribleme helps the information of the cortex and endodermis.
- Plerome helps in the formation of stellar tissue (pericycle, vascular bundle, medullary rays, and pith).
- Calyptrogen helps in the formation of root caps in monocot.
Thus meristematic tissue or meristem is a group of cells that have retained the power of division or continuous state of division. This is very essential tissue of plant life to grow and continue its lifecycle. From a stem, leaf, and root it is functional in every part of the plant. If you have any confusion related to this topic then feel free to comment.
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