Plant Tissue Systems — Dermal, Ground and Vascular
Detailed notes on the three plant tissue systems for Class 9 from the NCERT Exploration textbook (Chapter 3: Tissues in Action). Topics covered: why tissues are grouped into systems, the dermal tissue system (epidermis), the ground tissue system (parenchyma, collenchyma, sclerenchyma), and the vascular tissue system (xylem and phloem), with their locations in root, stem, and leaf. Aligned with CBSE syllabus 2026–27.
In the previous pages on meristematic tissue and permanent tissues, you studied the individual tissues of a plant — epidermis, parenchyma, collenchyma, sclerenchyma, xylem, and phloem. However, in a living plant, these tissues do not work in isolation. They are grouped together into larger, coordinated functional units called tissue systems.
Definition
A plant tissue system is a group of one or more tissues that together perform a common, coordinated function across the entire plant body — from root to stem to leaf. Organising tissues into systems allows the plant to carry out complex life processes (protection, support, photosynthesis, and transport) in a highly efficient and integrated manner.
Think of it this way: a single xylem strand in a leaf vein, the xylem bundle in the stem, and the xylem tissue in the root are all structurally similar and perform the same function — transporting water. Together, they form a continuous vascular tissue system that runs through the whole plant, from the roots to the topmost leaf. The same logic applies to the other two systems.
As stated in NCERT Exploration (Chapter 3), plant tissues are organised into three tissue systems:
Dermal Tissue System
Ground Tissue System
Vascular Tissue System
2. Dermal Tissue System
Q. What is the dermal tissue system and what does it do?
The dermal tissue system forms the outermost covering of the entire plant body. The word "dermal" means relating to the skin — just as skin covers the animal body, the dermal tissue system covers the plant body.
2.1 Composition
In young and herbaceous plants, the dermal tissue system consists of the epidermis — a single layer of flat, rectangular, tightly packed cells.
In older woody plants, the epidermis of the stem is replaced by cork (bark) — multi-layered dead cells produced by the cork cambium (a type of lateral meristem). Cork cells are impermeable to water and gases, providing stronger protection in mature plants.
2.2 Key Structures of the Dermal System
Structure
Location
Function
Epidermis
All surfaces (root, stem, leaf, flower)
Protection from mechanical injury, pathogens, and excessive water loss
Cuticle
Outer surface of epidermal cells (stems, leaves)
Waxy layer of cutin that reduces transpiration; thicker in desert plants
Stomata
Epidermis of leaves and green stems
Gaseous exchange (CO₂ in, O₂ out); transpiration — drives water transport through xylem
Root Hairs
Epidermis of roots
Increase surface area for absorption of water and minerals from soil
Cork (Bark)
Outer surface of old woody stems
Replaces epidermis in mature plants; impermeable, tough, insulates against temperature extremes
2.3 Functions of the Dermal Tissue System
Protection — guards all inner tissues against physical damage, excessive water loss, and invasion by pathogens and parasites.
Water regulation — the cuticle limits transpiration; stomata regulate it by opening and closing.
Absorption — root hairs in the dermal layer of roots absorb water and dissolved minerals by osmosis and diffusion.
Gas exchange — stomata allow the passage of carbon dioxide, oxygen, and water vapour necessary for photosynthesis and respiration.
3. Ground Tissue System
Q. What is the ground tissue system?
The ground tissue system forms the main body (bulk) of the plant. It occupies all the space between the dermal tissue system on the outside and the vascular tissue system at the centre or in bundles. The ground tissue system is the largest tissue system by volume in most plants.
Parenchyma — living cells with thin cellulosic walls and prominent intercellular spaces. Forms the largest proportion of the ground tissue. Found in the cortex and pith of stems and roots, and in the mesophyll (inner layer) of leaves.
Collenchyma — living cells with pectin-thickened corners. Found in the outer cortex of stems and in the margins and midrib of leaves. Provides flexible mechanical support.
Sclerenchyma — dead cells with thick lignified walls. Found scattered in the cortex, around vascular bundles, and in the pith of stems. Provides rigid structural support.
3.2 Functions of the Ground Tissue System
Food storage — parenchyma cells in the cortex, pith, and fleshy organs store starch, sugars, oils, and other nutrients.
Photosynthesis — the mesophyll of leaves (composed mainly of parenchyma with chloroplasts — chlorenchyma) is the primary site of photosynthesis in the plant. The internal structure of the sunflower stem shown in NCERT Fig. 3.7 clearly shows ground tissue occupied by parenchyma and collenchyma surrounding the vascular bundles.
Mechanical support — collenchyma provides flexibility; sclerenchyma provides rigidity. Together they hold the plant upright and resist mechanical stress (wind, weight of leaves and fruit).
Gas storage — in aquatic plants, parenchyma cells form aerenchyma (large air spaces), which provides buoyancy and stores gases for underwater photosynthesis and respiration.
Lateral transport — ground tissue parenchyma assists in the sideways movement of water, minerals, and food between the vascular system and other cells.
Ground Tissue in Different Organs
The ground tissue has different names depending on where it is located: cortex (outer region of root and stem between the epidermis and vascular tissue), pith (central region of stem, mainly parenchyma), and mesophyll (the inner tissue of leaves between the two epidermal layers). Despite the different names, they are all part of the same ground tissue system.
4. Vascular Tissue System
Q. What is the vascular tissue system?
The vascular tissue system is the transport system of the plant. It consists of the two complex permanent tissues — xylem and phloem — which run continuously through the entire plant body (roots, stem, and leaves), forming an interconnected network.
4.1 Composition
Xylem — composed of tracheids, vessels, xylem parenchyma, and xylem fibres. Transports water and dissolved minerals upward from roots to leaves. Mostly composed of dead cells; provides mechanical strength.
Phloem — composed of sieve tubes, companion cells, phloem parenchyma, and phloem fibres. Transports food (sugars) manufactured in leaves to all other parts of the plant. Mostly composed of living cells; transport is bidirectional (source to sink).
Xylem and phloem are bundled together in structures called vascular bundles. The arrangement of these bundles (and whether xylem and phloem are on the same side or opposite sides of the bundle) varies between roots, stems, and leaves.
4.2 Functions of the Vascular Tissue System
Water and mineral transport — xylem carries water absorbed by root hairs upward to all aerial parts of the plant. This upward movement is driven by the transpiration pull created when water evaporates through stomata in leaves.
Food transport — phloem carries the products of photosynthesis (primarily sucrose) from the leaves (source) to all non-photosynthetic parts — roots, growing buds, fruits, and seeds (sinks).
Structural support — the lignified walls of xylem tracheids and vessels and the sclerenchymatous phloem fibres add to the structural rigidity of stems and leaf veins.
Integration — the continuous network of vascular tissue through the entire plant body ensures that all parts — no matter how distant from the leaves or roots — receive water, minerals, and food.
Remember — Xylem and Phloem Always Travel Together
In most plants, xylem and phloem are always found together in vascular bundles — they never occur separately in the plant body. This packaging ensures that wherever water is transported (xylem), the food supply line (phloem) is also present to serve those cells, and vice versa. The leaf veins you can see when you hold a leaf up to light are vascular bundles.
5. Where Each System is Located — Root, Stem and Leaf
The three tissue systems are present in all plant organs, but their arrangement and relative proportions differ between root, stem, and leaf. This is based on Fig. 3.10 of the NCERT Exploration textbook, which shows cross-sections of these three organs.
5.1 In the Root
Dermal tissue system — outermost single layer (epidermis). Root hair cells extend from this layer into the soil to absorb water and minerals.
Ground tissue system — large zone of cortex (mostly parenchyma) between the epidermis and the central vascular cylinder. Stores water and nutrients; assists in moving water inward toward the xylem.
Vascular tissue system — located at the very centre of the root, in a compact structure called the stele. Xylem forms a star-shaped (radial) arrangement at the centre; phloem is positioned between the arms of the xylem star.
5.2 In the Stem
Dermal tissue system — outermost epidermis (with cuticle and stomata). In woody stems, replaced by cork (bark).
Ground tissue system — the cortex (between epidermis and vascular bundles) and the pith (central parenchyma mass). This is the bulk of the stem, clearly visible in Fig. 3.7 of the textbook showing the T.S. of a sunflower stem with parenchyma, collenchyma, and sclerenchyma all present.
Vascular tissue system — arranged as discrete vascular bundles scattered through the ground tissue (in monocot stems) or arranged in a ring near the outer edge (in dicot stems). Each bundle has xylem on the inner side and phloem on the outer side. The lateral meristem (vascular cambium) lies between xylem and phloem in dicot stems, enabling secondary growth in girth.
5.3 In the Leaf
Dermal tissue system — upper and lower epidermis (both surfaces of the leaf). Stomata are more numerous on the lower surface. The epidermis is transparent to allow light to reach the photosynthetic ground tissue below.
Ground tissue system — the mesophyll between the two epidermal layers. Composed almost entirely of parenchyma rich in chloroplasts (chlorenchyma). Divided into palisade mesophyll (tightly packed, columnar cells near the upper surface — primary photosynthesis site) and spongy mesophyll (loosely packed with large air spaces — gaseous exchange).
Vascular tissue system — the leaf veins (midrib and branching veins) that you can see clearly in any leaf. Each vein is a vascular bundle containing xylem (supplying water to mesophyll cells) and phloem (carrying away the sugars produced by photosynthesis).
6. Summary Table — Three Plant Tissue Systems
Tissue System
Tissues / Cell Types Included
Main Functions
Location in Plant
Dermal Tissue System
Epidermis (cuticle, stomata, root hairs); Cork in mature stems
Protection from injury, water loss, pathogens; water absorption (root hairs); gas exchange (stomata)
Transport of water & minerals upward (xylem); transport of food bidirectionally (phloem); mechanical strength (lignified walls)
Central stele in root; vascular bundles in stem; leaf veins in leaf
7. Quick Revision — 4 Key Points
Tissues in plants are not isolated — they are organised into three coordinated tissue systems that run continuously through the entire plant body: dermal, ground, and vascular.
The dermal tissue system (epidermis and cork) forms the outermost protective covering of the plant. Key specialisations: cuticle (water retention), stomata (gas exchange & transpiration), and root hairs (water absorption).
The ground tissue system (parenchyma, collenchyma, sclerenchyma) makes up the bulk of the plant between the dermal and vascular systems — it handles food storage, photosynthesis (mesophyll), and mechanical support (flexible by collenchyma; rigid by sclerenchyma).
The vascular tissue system (xylem + phloem, bundled together) is the long-distance transport network of the plant — xylem carries water upward; phloem carries food in both directions. Together they ensure every cell in the plant is connected to both the water supply and the food supply.
Related Concepts from Chapter 2 (Cell: The Building Block of Life)
Plant tissue systems are built from individual cells. Review these Chapter 2 pages to strengthen your understanding of how cell structure supports tissue system function:
Cell Wall — the cell wall of dermal cells is modified into cuticle; sclerenchyma cell walls are lignified; xylem vessel walls are heavily lignified — all rooted in cell wall chemistry
Osmosis and Diffusion — water absorption by root hairs (dermal system) occurs by osmosis; the transpiration pull in the vascular system is driven by the same principles
Cell Organelles — chloroplasts in ground tissue (chlorenchyma of mesophyll) perform photosynthesis; mitochondria in companion cells power active loading of sugars into phloem
Mitosis — the lateral meristem in the vascular tissue system (vascular cambium) divides by mitosis to add new xylem and phloem cells, increasing stem girth
Cell Membrane — selective permeability of the cell membrane controls what enters and exits cells in all three tissue systems
Cell — Basic Unit of Life — foundational understanding of the cell as the building block of all tissue systems
