Detailed notes on meristematic tissue for Class 9 from the NCERT Exploration textbook (Chapter 3: Tissues in Action). Topics covered: definition, characteristics of meristematic cells, three types (apical, lateral, intercalary), their locations, functions, and how differentiation leads to permanent tissues. Aligned with CBSE syllabus 2026-27.
All living organisms grow. In plants, growth does not happen uniformly all over the body — it is confined to specific regions where cells are constantly dividing. These regions are made up of a specialised type of plant tissue called meristematic tissue.
Meristematic tissue is a group of actively dividing cells found at specific locations in a plant body. These cells have the ability to undergo continuous cell division (mitosis), adding new cells to the plant and enabling it to grow in length, girth, and to regenerate after damage.
The word "meristem" comes from the Greek word meristos, meaning divisible — which directly reflects the key property of these cells: they can divide.
Plants grow in ways that require very different types of cell activity. A small seedling grows into a tall tree; roots push deeper and deeper into the soil; grass regrows after being grazed. These different growth patterns require dedicated regions of actively dividing cells.
As stated in the NCERT Exploration textbook (Chapter 3), plants grow in three distinct ways:
Each of these three types of growth is driven by a different type of meristematic tissue. Without these actively dividing regions, plants would be unable to grow or repair themselves throughout their lives.
Unlike animals, in which most tissues can divide and grow throughout the body, plant growth is localised — it occurs only in specific meristematic regions. This is one of the fundamental differences between plant and animal growth.
Meristematic cells have a distinctive structure that enables them to divide rapidly and continuously. Each structural feature has a specific reason behind it.
| Characteristic | Description | Reason / Significance |
|---|---|---|
| Cell wall | Thin and cellulosic | A thin wall allows the cell to expand and divide quickly without restriction. |
| Cytoplasm | Dense and packed with many organelles | Dense cytoplasm supports high metabolic activity needed for rapid cell division. |
| Nucleus | Large and prominent | A large nucleus controls active cell division and the intense genetic activity required for mitosis. |
| Vacuoles | Generally absent | Absence of vacuoles leaves more space for the nucleus and cytoplasm, and also prevents the cell from becoming too rigid to divide. Vacuoles would store water and create turgor pressure that could interfere with cell division. |
| Cell packing | Tightly packed with little or no intercellular space | Close packing ensures efficient communication and mechanical support between dividing cells. |
| Shape & size | Small, isodiametric (equal dimensions on all sides) | Small, uniformly shaped cells can divide in multiple directions to produce new cells in any orientation. |
The absence of vacuoles is a defining feature of meristematic cells. As cells differentiate into permanent tissues, vacuoles develop and gradually enlarge. A large central vacuole is a hallmark of mature plant cells.
Based on their location in the plant body and the type of growth they bring about, meristematic tissues are classified into three types:
Q. What is apical meristem and where is it located?
The apical meristem is the meristematic tissue located at the tips (apex) of roots and shoots. It is responsible for the primary growth of a plant — that is, growth in length.
In Activity 3.1 of your NCERT textbook, two onion bulbs are placed in jars of water. After a few days, the root tips of one bulb (Jar B) are cut by about 1 cm, while the other (Jar A) is left undisturbed.
You may recall that in Chapter 2, you observed mitosis in onion root tips — this further confirms that root tips are regions of active cell division.
Q. What is lateral meristem and how does it cause the stem to become thicker?
The lateral meristem is the meristematic tissue arranged in a ring along the circumference (lateral sides) of the stem. It is responsible for secondary growth — that is, increase in girth or diameter of the stem and roots.
Q. What are annual growth rings and what do they tell us?
If you have visited a timber yard or seen a tree trunk that has been cut, you would have noticed several ring-like patterns on the cross-section (transverse section) of the wood. These are called annual growth rings.
Scientists have used annual growth rings in ancient trees to reconstruct climate records going back thousands of years. The study of tree rings — dendrochronology — can reveal information about past droughts, volcanic eruptions, and even solar activity.
Q. What is intercalary meristem and why is it important for grasses?
The intercalary meristem is the meristematic tissue located at the base of internodes or just above the nodes of certain plants, particularly grasses. It enables plants to regrow after being cut or grazed.
Examples from everyday life:
Grasslands — which cover vast areas of the Earth — depend entirely on the intercalary meristem of grass plants. Without this tissue, grasslands would be destroyed by grazing animals and would not recover. The intercalary meristem ensures that grasses can survive repeated grazing and mowing, making them one of the most resilient plant types on Earth.
| Feature | Apical Meristem | Lateral Meristem | Intercalary Meristem |
|---|---|---|---|
| Location | Tips of roots and shoots (apex) | Along the circumference of stems and roots | Base of internode / just above the node |
| Direction of growth | Upward (shoot) / Downward (root) — linear | Outward (radial) — concentric rings | Upward — intercalated between mature regions |
| Function | Increase in length (primary growth) | Increase in girth / diameter (secondary growth) | Regrowth after cutting or grazing |
| Type of growth | Primary | Secondary | Primary (restorative) |
| Plants where prominent | All vascular plants (roots and shoots) | Mainly dicot plants (woody stems) | Grasses, monocots, hedges |
| Example | Onion root tip, growing shoot of mango sapling | Tree trunk (produces annual rings), vascular cambium | Grass blade, hedge plants (e.g., hibiscus) |
Meristematic cells divide continuously to add new cells. However, not all newly formed cells remain meristematic forever. The newly produced cells eventually face one of two fates:
Q. What is differentiation?
The process by which meristematic cells lose the ability to divide and become specialised to perform a specific function is called differentiation. The result of differentiation is permanent tissue.
Meristematic tissue (dividing, undifferentiated)
⟶ Cells stop dividing and change in structure and function
⟶ Permanent tissue (non-dividing, specialised)
Permanent tissues are specialised to perform specific functions such as support (collenchyma, sclerenchyma), storage and photosynthesis (parenchyma), or transport (xylem, phloem). Read about these in detail on the Permanent Tissues page.
Once a cell has differentiated into a permanent tissue, this change is generally irreversible — the cell cannot return to the meristematic state under normal conditions. This is why the active meristematic regions are so critical for plant growth throughout the plant's life.
The standard diagram used in examinations for meristematic tissue is a simple line drawing of a young sapling showing both the root and shoot. Below is a guide to labelling this diagram correctly (refer to Fig. 3.3 in your NCERT Exploration textbook, Chapter 3).
At the top (Shoot region):
At the bottom (Root region):
Key labelling instruction: Always draw arrows pointing precisely to the location of the meristem — at the extreme tip for root and shoot. Do not label the entire root or stem as meristematic.
In board examinations, when asked to label the diagram of a sapling showing meristematic tissue, you must correctly identify the shoot apical meristem (at the shoot tip) and the root apical meristem (at the root tip). The lateral meristem is shown in transverse section (T.S.) of a stem as a ring of cells between the xylem and phloem (vascular cambium). The intercalary meristem is shown in a grass stem diagram at the base of the internode/above the node.
Understanding meristematic tissue builds directly on your knowledge of cells. Review these related pages: