Meristematic tissue class 9 – This post outlines the basic functions and location of meristematic tissues in plants. Carl Wilhelm von Nägeli coined the term “meristem.” Further, Meristematic tissue contains undifferentiated cells, which are the building blocks of the specialized plant structures.

Meristematic tissues contain living cells with varied shapes. They possess a large nucleus devoid of the vacuole. The cells have no intercellular space. Further, the zone in which these cells exist is “meristem.”

The cells of the meristematic tissue divide actively to form specialized structures such as buds of leaves and flowers, tips of roots and shoots, etc. These cells help to increase the length and girth of the plant.

Characteristics of Meristematic Tissue

The characteristics of meristematic tissue are as follows:

1. The meristematic tissue has the quality of self-renewal. Every time the cell divides, one cell remains identical to the parent cell, and the others form specialized structures.
2. Further, they have very small and few vacuoles.
3. The meristematic tissue is living and thin-walled.
4. The protoplasm of the cells is very dense.
5. The meristematic tissues also heal the wounds of an injured plant.
6. The cells of the meristematic tissue are young and immature.
7. Further, they do not store food.
8. Exhibit a very high metabolic activity.
9. They also possess a single, large and prominent nucleus.

Types of Meristematic Tissue

The meristematic tissue is of the following types:

Meristematic Tissue On the basis of Origin

Promeristem

• The earliest and youngest meristematic tissue.
• It originates from the embryo.
• Further, the primary meristem arises from the promeristem.
• Found in the root and the shoot tips.

Primary Meristem

• It arises from the promeristem.
• Cells then divide actively.
• It is present below the promeristem and forms the permanent tissue.

Secondary Meristem

• It originates from the primary meristem.
• The permanent tissue forms from the secondary meristem.

Meristematic Tissue On the Basis of Position

Apical Meristem

• These are present at the tips of the roots and shoots and helps in the increase of the height of the plants.
• Various cell divisions facilitate the growth of the cells in the roots and shoots and help in cellular enlargement.
• Further, apical meristem is divided into-promeristem zone, which contains actively dividing cells, and the meristematic zone, which contains protoderm, procambium and ground meristem.

Intercalary Meristem

• It is located in the leaves and internodes at the intercalary position.
• These also help to increase the length of the internode.
• It is found in grass, monocots and pines.
• Further, it is a part of apical meristem and adds to the height of the plant.

Lateral Meristem

• It is located in the stems and roots on the lateral side.
• Further, it increases the thickness of the plant.
• Vascular cambium and cork cambium are the two lateral meristems.
• These divide preclinically or radially and give rise to secondary permanent tissues.

Meristematic Tissue On the Basis of Function

Protoderm

• It is the outermost plant tissue and forms the epidermis.
• It protects the plants from any mechanical shocks.

Procambium

• It is the innermost tissue and gives rise to xylem and phloem.
• It helps in the transport of water and nutrients to different parts of the plant.

Ground Meristem

• The cells are large with thick walls.
• It forms the cortex, pericycle and pith.

Conclusion

Meristematic tissue class 9 – This post has laid down the basic functions and location of meristematic tissues in plants. Further, the meristematic tissue is usually found in the apices of the root systems and the shoots and is in a continuous state of division.

Also read: Control and Coordination Class 10 Notes Science Chapter 7

Questions and Answers

Q1. What is a meristematic tissue?

Answer: Meristematic tissue divides throughout their life. They are located in the specific regions of the plant.
Cells of this tissue are very active, have dense cytoplasm, thin walls, and prominent nuclei. They lack vacuoles. The cell wall is cellulosic.

Q2. Meristematic tissue is found in the growing tips of ________ and ________.

Answer: Meristematic tissues, or simply meristems, are tissues in which the cells remain forever young and divide actively throughout the life of the plant. When a meristematic cell divides in two, the new cell that remains in the meristem is called an initial, the other the derivative. As new cells are added by repeated mitotic divisions. These types of tissues are generally found in the extreme regions i.e root and shoot tip that has to grow continuously.
A plant has four kinds of meristems: the apical meristem and three kinds of lateral—vascular cambium, cork cambium, and intercalary meristem.
The meristem which is located at opposite ends of the plant axis in the tips of roots and shoots. is known as the apical meristem.

Questions and Answers

Q3. Meristematic tissue occurs in

A. Stem
B. Roots
C. All growing tips
D. Both A & B

Answer: Meristem is the region marked by the presence of active cell growth and the tissues present in meristem are termed as meristematic tissues.
On the basis of their position in the plant body, meristems are grouped as apical, lateral or intercalary meristem.
Stem has apical meristem in the shoot apex, intercalary meristem in nodes and lateral meristem in form of cambium in vascular bundles.
Roots have apical meristem root apex and lateral meristem in form of cambium in vascular bundles. Shoot and root tips are the growing tips of a plant. Due to presence of root cap in terminal position, root apical meristem is subterminal in position thus, not all the growing tips have meristem.
Therefore, the correct answer is option D.

Q4. Intercalary meristem is derived from

1. Protoderm
2. Calyptrogens
3. Laterl meristem
4. Apical meristem

Answer: 4

Questions and Answers

Q5. The term meristem was given by

1. Nageli
2. Cohn
3. Hanstein
4. Schmidt

Answer: 1

Q6. Apical meristems are found in animals. Is it True or False?

Answer: False. Apical meristems are found in plants. They help in the increase of the height of a plant.

Q7. Stem of date palm increases in girth due to activity of ___________

1. Intercalary Meristem
2. Apical Meristem
3. Both of the above
4. None of the above

Answer. Most monocots either have no secondary growth or else anomalous secondary growth of some type. For example, palm trees increase their trunk diameter due to division and enlargement of parenchyma cells, which is termed as ‘diffuse secondary growth’.

In some other monocot stems with anomalous secondary growth, a cambium forms but it produces vascular bundles and parenchyma internally and just parenchyma externally. Some monocot stems increase in diameter due to the activity of a primary thickening meristem, which derives itself from the apical meristem.

The stem of date palm increases in girth due to the activity of apical meristem and not because of intercalary meristem and lateral meristem (involves is the normal secondary growth of dicots). Thus, option B is correct.