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The Tissue System

BiologyAnatomy of Flowering PlantsFor NEET aspirants

Plant tissues are grouped into a tissue system on the basis of their structure and location. This page explains the three tissue systems of flowering plants: epidermal, ground and vascular. It covers the epidermis, cuticle, stomata, guard cells, subsidiary cells, root hairs, trichomes and mesophyll. It also covers radial, conjoint, open and closed vascular bundles, as given in the NCERT Class 11 chapter on anatomy of flowering plants. NEET often tests each tissue system through match-the-list and statement questions on stomata and bundle types.

On this page1Plant anatomy2Three tissue systems3Epidermal system4Ground system5Vascular system6Exam essentials7Practice
Key Points at a Glance
  1. ★ Must learn Anatomy: the study of the internal structure of plants.
  2. ★ Must learn Three tissue systems by structure and location: epidermal, ground (fundamental) and vascular (conducting).
  3. The epidermis is usually single-layered; its cells are parenchymatous with a large vacuole.
  4. The waxy cuticle prevents water loss; it is absent in roots.
  5. ★ Must learn Stomatal apparatus = stomatal aperture + guard cells + surrounding subsidiary cells.
  6. Guard cells are bean-shaped; in grasses they are dumb-bell shaped.
  7. Guard cells: outer walls thin, inner walls (towards the pore) highly thickened; they possess chloroplasts.
  8. Root hairs are unicellular; shoot trichomes are usually multicellular.
  9. Ground tissue: all tissues except the epidermis and vascular bundles; in leaves it is the mesophyll.
  10. ★ Must learn Open bundle: cambium present (dicot stems); closed bundle: no cambium (monocots).
  11. ★ Must learn Radial: xylem and phloem on different radii (roots); conjoint: on the same radius (stems, leaves).

1. Plant Anatomy: An Introduction

1.1 What anatomy studies

  • Like external morphology, the internal structure of plants also shows several similarities and differences.
  • ★ Exam imp Anatomy: the study of the internal structure of plants.
  • It deals with the internal structure and functional organisation of higher plants.

Plants are built up in levels:

  1. Cells are the basic unit of the plant body.
  2. Cells are organised into tissues.
  3. Tissues, in turn, are organised into organs.
  • Different organs of a plant show differences in their internal structure.
  • Within angiosperms, monocots and dicots are anatomically different.
  • Internal structures also show adaptations to diverse environments.

1.2 Plant tissues in brief

  • A plant is anatomically made of different kinds of tissues.
  • Tissues are broadly classified into meristematic and permanent tissues.
Class of tissueTypes
MeristematicApical, lateral and intercalary
PermanentSimple and complex

Main functions of plant tissues:

  • Assimilation of food and its storage.
  • Transportation of water, minerals and photosynthates.
  • Mechanical support.

Extra Depth: A simple tissue is made of only one type of cell (parenchyma, collenchyma, sclerenchyma). A complex tissue is made of more than one type of cell (xylem, phloem). Both terms are used in the tissue systems below.

Memory Trick

Meristematic tissues: "All Lions Interact" = Apical, Lateral, Intercalary. Permanent tissues are of two kinds: Simple and Complex.

Key idea
Anatomy studies internal structure: cells form tissues, tissues form organs, and monocots and dicots differ inside.

2. The Three Tissue Systems

  • Tissues vary depending on their location in the plant body.
  • Their structure and function also depend on this location.
  • ★ Exam imp On the basis of structure and location, there are three tissue systems.
Tissue systemAlso calledMade of
Epidermal tissue system-Epidermal cells, stomata and epidermal appendages (trichomes and hairs)
Ground tissue systemFundamental tissue systemSimple tissues: parenchyma, collenchyma and sclerenchyma
Vascular tissue systemConducting tissue systemComplex tissues: xylem and phloem
Memory Trick

The three systems in order: Every Good Vine = Epidermal, Ground, Vascular. The other names pair up as Ground = Fundamental and Vascular = Conducting.

Key idea
Three tissue systems, grouped by structure and location: epidermal, ground (fundamental) and vascular (conducting).

3. Epidermal Tissue System

  • It forms the outermost covering of the whole plant body.
  • It comprises epidermal cells, stomata and the epidermal appendages (trichomes and hairs).

3.1 Epidermis and cuticle

  • Epidermis: the outermost layer of the primary plant body.
  • It is made of elongated, compactly arranged cells that form a continuous layer.
  • ★ Exam imp The epidermis is usually single-layered.
  • Epidermal cells are parenchymatous, with a small amount of cytoplasm lining the cell wall and a large vacuole.
  • Cuticle: a thick, waxy layer that often covers the outside of the epidermis.
  • The cuticle prevents the loss of water.
  • ★ Exam imp The cuticle is absent in roots.

3.2 Stomata

  • Stomata are structures present in the epidermis of leaves.
  • They regulate transpiration and gaseous exchange.
  • Each stoma has two bean-shaped cells called guard cells, which enclose the stomatal pore.
  • ★ Exam imp In grasses, the guard cells are dumb-bell shaped.
  • The outer walls of guard cells (away from the stomatal pore) are thin.
  • The inner walls of guard cells (towards the stomatal pore) are highly thickened.
  • Guard cells possess chloroplasts and regulate the opening and closing of stomata.
  • Subsidiary cells: sometimes, a few epidermal cells near the guard cells become specialised in shape and size.

★ Very important Stomatal apparatus = the stomatal aperture (pore) + the guard cells + the surrounding subsidiary cells.

Stoma with bean-shaped guard cells Surface view of a leaf epidermis with one stoma: two bean-shaped guard cells containing chloroplasts surround a central stomatal pore, with subsidiary cells and ordinary epidermal cells around them. Epidermalcells Subsidiarycells Chloroplast Stomatal pore Guard cells
Figure 1: A stoma with bean-shaped guard cells. Two guard cells with chloroplasts enclose the stomatal pore, and subsidiary cells lie between them and the epidermal cells.
Stoma with dumb-bell shaped guard cells, as in grasses Surface view of a grass leaf epidermis. Long epidermal cells lie in files. In the middle, two subsidiary cells flank a pair of dumb-bell shaped guard cells. Each guard cell has bulbous ends with chloroplasts and a narrow middle with thick inner walls. The slit between the two narrow middles is the stomatal pore. Epidermal cells Chloroplast Subsidiary cell Stomatal pore Guard cell (dumb-bell shaped)
Figure 2: A stoma with dumb-bell shaped guard cells, as in grasses. The narrow middles of the two guard cells border the stomatal pore.
Bean-shaped guard cells
  • The usual shape of guard cells.
  • Two bean-shaped cells enclose the pore.
  • See Figure 1.
Dumb-bell shaped guard cells
  • Seen in grasses.
  • Bulbous ends with a narrow middle.
  • See Figure 2.
Memory Trick

Parts of a stomatal apparatus: Pore, Guard cells, Subsidiary cells. Recall them as "Please Guard Secrets".

Tips and Tricks Thick In, Thin Out: the guard cell wall facing the pore is thick; the wall away from the pore is thin. In a statement question, swap the two words and the statement becomes false.
Quick Recall: tap to check
Name the three parts of a stomatal apparatus.
The stomatal aperture (pore), the guard cells and the surrounding subsidiary cells.
Which wall of a guard cell is highly thickened?
The inner wall, which faces the stomatal pore. The outer wall is thin.
In which plants are the guard cells dumb-bell shaped?
In grasses.
In Figure 2, name the slit between the narrow middles of the two guard cells.
The stomatal pore.

3.3 Epidermal hairs: root hairs and trichomes

  • The cells of the epidermis bear a number of hairs.
  • ★ Exam imp Root hairs: unicellular elongations of the epidermal cells of the root.
  • Root hairs help absorb water and minerals from the soil.
  • Trichomes: the epidermal hairs on the stem.
  • Trichomes of the shoot system are usually multicellular.
  • They may be branched or unbranched, and soft or stiff.
  • They may even be secretory.
  • Trichomes help prevent water loss due to transpiration.
FeatureRoot hairsTrichomes
LocationEpidermis of the rootEpidermis of the stem (shoot system)
Number of cellsUnicellularUsually multicellular
FormSimple elongations of epidermal cellsBranched or unbranched; soft or stiff; may be secretory
FunctionAbsorb water and minerals from the soilHelp prevent water loss due to transpiration
Memory Trick

Roots take in, shoots hold in. Root hairs (one cell) absorb water; trichomes (many cells) reduce water loss.

Key idea
The epidermis covers the plant; the cuticle saves water, stomata exchange gases, and hairs absorb (root) or conserve (shoot) water.

4. Ground Tissue System

  • ★ Exam imp Ground tissue: all tissues except the epidermis and the vascular bundles.
  • It consists of the simple tissues parenchyma, collenchyma and sclerenchyma.
  • In primary stems and roots, parenchymatous cells are usually present in the cortex, pericycle, pith and medullary rays.
  • In leaves, the ground tissue consists of thin-walled, chloroplast-containing cells.
  • This ground tissue of leaves is called the mesophyll.
  • The ground tissue system forms the main bulk of the plant.
  • It is divided into three zones: cortex, pericycle and pith.

★ Very important Ground tissue = everything except the epidermis and the vascular bundles. In a leaf, it is the mesophyll.

Memory Trick

Parenchyma of primary stems and roots sits in the Cortex, Pericycle, Pith and Medullary rays: "Cats Prefer Plain Milk".

Key idea
Ground tissue is the bulk of the plant: simple tissues in the cortex, pericycle and pith, and the mesophyll in leaves.

5. Vascular Tissue System

  • The vascular system consists of the complex tissues phloem and xylem.
  • The xylem and phloem together constitute the vascular bundles.
  • The vascular bundles form the conducting tissue; they translocate water, minerals and food material.
  • Bundle types depend on the presence of cambium and on the location of xylem and phloem.

Extra Depth: elements of xylem and phloem. Xylem and phloem are complex tissues. Each is made of more than one type of cell (Figures 3 and 4).

  • Xylem conducts water and minerals from the roots to the stem and leaves. It also gives mechanical support.
  • Tracheids: elongated cells with thick, lignified walls and tapering ends; dead and without protoplasm.
  • Vessels: long tubes made of many cells called vessel members, linked through perforations in their common walls; dead at maturity.
  • Vessels are a characteristic feature of angiosperms; gymnosperms lack them.
  • Pits: thin areas in the thick walls through which water passes between neighbouring cells.
  • Xylem parenchyma: living, thin-walled cells that store food such as starch and fat.
  • Xylem fibres have very thick walls and an obliterated central lumen.
  • Phloem transports food, usually from the leaves to other parts of the plant.
  • Sieve tube elements: tube-like cells joined end to end; their perforated end walls form sieve plates with many sieve pores.
  • A mature sieve tube element has peripheral cytoplasm and a large vacuole but no nucleus.
  • Companion cells: specialised parenchyma cells beside the sieve tube elements; their nuclei control the sieve tubes.
  • Phloem parenchyma: living cells that store food; absent in most monocots.
  • Phloem fibres (bast fibres) are dead sclerenchyma cells with thick walls.
Elements of xylem Three-dimensional view of a block of xylem: wide vessels divided by end walls, narrow tracheids with tapering overlapping ends, pits on the cell walls, and a row of xylem parenchyma cells with nuclei along one side Pits Vessel Tracheids Xylem parenchyma
Figure 3: Elements of xylem: wide vessels, narrow tracheids with tapering ends, pits in their walls, and living xylem parenchyma.
Elements of phloem Three-dimensional view of a block of phloem: two sieve tube elements joined end to end by sieve plates, narrow companion cells with nuclei beside them, and phloem parenchyma cells along one side; an inset shows the surface view of a sieve plate with many sieve pores and an attached companion cell Sieve pores Companioncell Sieve plate Sieve tube element Companion cell Phloem parenchyma Sieve plate
Figure 4: Elements of phloem: sieve tube elements joined end to end at sieve plates, with companion cells and phloem parenchyma beside them. Inset: surface view of a sieve plate with its sieve pores.

5.1 Open and closed vascular bundles

  • In dicotyledonous stems, cambium is present between the phloem and the xylem.
  • Because of the cambium, such bundles can form secondary xylem and phloem tissues.
  • ★ Exam imp Open vascular bundles: bundles with cambium, as in dicot stems.
  • In monocotyledons, the vascular bundles have no cambium.
  • So they do not form secondary tissues and are called closed vascular bundles.

★ Very important Cambium decides open or closed. Cambium present: open (dicot stem). Cambium absent: closed (monocots).

5.2 Radial and conjoint vascular bundles

  • Radial arrangement: xylem and phloem lie in an alternate manner along different radii.
  • ★ Exam imp Radial bundles are found in roots.
  • Conjoint bundles: xylem and phloem lie jointly along the same radius.
  • Conjoint bundles are common in stems and leaves.
  • In conjoint bundles, the phloem is usually located only on the outer side of the xylem.
Types of vascular bundles Three vascular bundles. (a) Radial: in a round stele, four xylem patches and four phloem patches lie on different radii, alternating with each other, as in roots. (b) Conjoint closed: phloem forms an outer cap directly over the xylem on the same radius, with no cambium, as in monocot stems. (c) Conjoint open: a strip of cambium lies between the outer phloem and the inner xylem, as in dicot stems. (a) Radial roots (b) Conjoint closed monocot stems (c) Conjoint open dicot stems Xylem Phloem Phloem Xylem Phloem Cambium Xylem
Figure 5: Types of vascular bundles: (a) radial, (b) conjoint closed and (c) conjoint open. Only the open bundle has cambium between the phloem and the xylem.
Bundle typeXylem and phloemCambiumFound in
RadialAlternate, on different radiiNone between them; in the dicot root a cambium ring develops laterRoots
Conjoint closedSame radius; phloem outside xylemAbsent; no secondary tissuesMonocots
Conjoint openSame radius; phloem outside xylemPresent between phloem and xylemDicot stems
Memory Trick

Roots go Radial; Stems and leaves Share a radius (conjoint). An open bundle stays open to further growth because it keeps its cambium.

NEET Focus
  • Dicot stem: conjoint and open. Monocots: conjoint and closed. Roots: radial.
  • A common false statement: "Radial bundles are common in stems." Correct: radial bundles occur in roots.
  • Another trap: "Closed bundles form secondary xylem." Correct: only open bundles, which have cambium, form secondary tissues.
Quick Recall: tap to check
Which tissue makes a vascular bundle open?
Cambium, present between the phloem and the xylem.
Name the type of vascular bundle found in roots.
Radial: xylem and phloem lie on different radii.
In a conjoint bundle, where does the phloem usually lie?
Only on the outer side of the xylem.
In Figure 5 (c), name the strip between the phloem and the xylem.
Cambium.
Key idea
Radial bundles belong to roots; conjoint bundles to stems and leaves, open with cambium in dicot stems and closed in monocots.

6. Exam Essentials

Pairs to Match

List IList II
Epidermal tissue systemEpidermal cells, stomata, trichomes and hairs
Ground tissue systemParenchyma, collenchyma and sclerenchyma
Vascular tissue systemXylem and phloem
CuticlePrevents water loss; absent in roots
Guard cells of grassesDumb-bell shaped
Inner wall of a guard cellHighly thickened, towards the pore
Subsidiary cellsSpecialised epidermal cells near the guard cells
StomataRegulate transpiration and gaseous exchange
Root hairsUnicellular; absorb water and minerals
TrichomesUsually multicellular; prevent water loss
MesophyllChloroplast-containing ground tissue of leaves
Open vascular bundleCambium present; dicot stems
Closed vascular bundleNo cambium; monocots
Radial vascular bundleRoots
Conjoint vascular bundleStems and leaves
Exceptions
  • The cuticle is absent in roots.
  • Guard cells are bean-shaped, except in grasses, where they are dumb-bell shaped.
  • Root hairs are unicellular, unlike shoot trichomes, which are usually multicellular.
  • Ground tissue includes every tissue except the epidermis and the vascular bundles.
  • Monocot bundles have no cambium, so they do not form secondary tissues.
  • The epidermis is usually single-layered, and conjoint bundles usually have phloem only on the outer side.

Numbers to Remember

  • 3 tissue systems: epidermal, ground and vascular.
  • 2 guard cells in each stoma.
  • 1 layer: the usual thickness of the epidermis.
  • 1 cell: a root hair is unicellular.
  • 3 simple tissues in the ground tissue; 2 complex tissues in the vascular system.
  • 3 types of meristematic tissue (apical, lateral, intercalary); 2 of permanent tissue (simple, complex).
  • 3 zones of the ground tissue system: cortex, pericycle and pith.
Quick Recall: tap to check
Which tissue system includes the mesophyll?
The ground tissue system.
Are trichomes on the shoot usually unicellular or multicellular?
Usually multicellular.
Where is the cuticle absent?
In roots.
Key idea
Learn each structure with its exact partner: NEET pairs these facts in match lists and hides the exceptions in statements.

7. Quick Revision

  • Anatomy: the study of the internal structure of plants.
  • Cells form tissues; tissues form organs.
  • Tissues: meristematic (apical, lateral, intercalary) and permanent (simple, complex).
  • Three tissue systems: epidermal, ground (fundamental), vascular (conducting).
  • Epidermis: usually single-layered, parenchymatous, large vacuole.
  • Cuticle: waxy; prevents water loss; absent in roots.
  • Stomata: regulate transpiration and gaseous exchange.
  • Guard cells: bean-shaped; dumb-bell shaped in grasses; contain chloroplasts.
  • Guard cell walls: inner thick, outer thin.
  • Stomatal apparatus: pore, guard cells and subsidiary cells.
  • Root hairs: unicellular; trichomes: usually multicellular, may be secretory.
  • Ground tissue: all except epidermis and vascular bundles; mesophyll in leaves.
  • Open bundles have cambium (dicot stems); closed bundles lack it (monocots).
  • Radial bundles: roots; conjoint bundles: stems and leaves, phloem outside xylem.

8. Solved Examples

Solved Example 1
Match List I with List II.
List I: A. Cuticle; B. Subsidiary cells; C. Trichomes; D. Mesophyll
List II: I. Ground tissue of leaves with chloroplasts; II. Absent in roots; III. Usually multicellular hairs of the shoot; IV. Specialised epidermal cells near the guard cells
Choose the correct answer.
(A) A-II, B-IV, C-III, D-I
(B) A-IV, B-II, C-III, D-I
(C) A-II, B-III, C-IV, D-I
(D) A-I, B-IV, C-III, D-II
Solution:

Answer: (A). The cuticle is absent in roots, and subsidiary cells are specialised epidermal cells beside the guard cells. Shoot trichomes are usually multicellular, and the mesophyll is the chloroplast-containing ground tissue of leaves.

Solved Example 2
Read the statements about the epidermal tissue system.
A. The epidermis is usually multi-layered.
B. The outer walls of guard cells are thin.
C. Guard cells possess chloroplasts.
D. Root hairs are multicellular.
E. Trichomes may be secretory.
Choose the correct answer.
(A) A, B and C only
(B) B, C and E only
(C) B, D and E only
(D) C, D and E only
Solution:

Answer: (B). A is false: the epidermis is usually single-layered. D is false: root hairs are unicellular elongations of epidermal cells. B, C and E are true.

Solved Example 3
Arrange these structures from the stomatal pore outwards.
A. Subsidiary cell; B. Stomatal pore; C. Epidermal cell; D. Guard cell
Choose the correct order.
(A) B, A, D, C
(B) B, D, A, C
(C) D, B, A, C
(D) B, D, C, A
Solution:

Answer: (B). The pore lies in the centre and is enclosed by the guard cells. Subsidiary cells lie around the guard cells, and ordinary epidermal cells surround the whole apparatus.

Solved Example 4
Which of the following is NOT a part of the ground tissue system?
(A) Pith
(B) Pericycle
(C) Epidermis
(D) Medullary rays
Solution:

Answer: (C). Ground tissue includes all tissues except the epidermis and the vascular bundles. Parenchyma occurs in the cortex, pericycle, pith and medullary rays.

Solved Example 5
Statement I: The vascular bundles of monocotyledons are called closed.
Statement II: Monocot vascular bundles have no cambium, so they do not form secondary tissues.
Choose the correct answer.
(A) Both Statement I and Statement II are correct
(B) Both Statement I and Statement II are incorrect
(C) Statement I is correct but Statement II is incorrect
(D) Statement I is incorrect but Statement II is correct
Solution:

Answer: (A). Both are correct. The absence of cambium is the reason the bundles are closed.

9. Practice Questions

Practice Questions
  1. What is a stomatal apparatus? Explain the structure of stomata with a labelled diagram.Answer: The stomatal apparatus is the stomatal aperture, the guard cells and the surrounding subsidiary cells. Each stoma has two bean-shaped guard cells (dumb-bell shaped in grasses) enclosing the pore. Their outer walls are thin, their inner walls are highly thickened, and they contain chloroplasts. Label the epidermal cells, subsidiary cells, chloroplast, guard cells and stomatal pore, as in Figures 1 and 2.
  2. Name the three basic tissue systems in flowering plants. Give the tissue names under each system.Answer: Epidermal tissue system: epidermal cells, stomata and epidermal appendages (trichomes and hairs). Ground tissue system: parenchyma, collenchyma and sclerenchyma. Vascular tissue system: xylem and phloem.
  3. How is the study of plant anatomy useful to us?Answer: It shows how cells form tissues and organs and how organs differ inside. It helps tell monocots from dicots, explains the adaptations of internal structure to diverse environments, and relates tissues to functions such as transport, support, gaseous exchange and water conservation.
  4. Match List I with List II. List I: A. Radial bundle; B. Conjoint open bundle; C. Conjoint closed bundle; D. Cambium. List II: I. Monocots; II. Roots; III. Dicot stems; IV. Forms secondary xylem and phloem.
    (1) A-II, B-III, C-I, D-IV
    (2) A-III, B-II, C-I, D-IV
    (3) A-II, B-I, C-III, D-IV
    (4) A-IV, B-III, C-I, D-IIAnswer: (1). Radial bundles occur in roots, open bundles in dicot stems and closed bundles in monocots; cambium forms secondary tissues.
  5. Read the statements. A. Ground tissue includes the epidermis. B. Parenchyma is present in the medullary rays. C. The mesophyll is the ground tissue of leaves. D. Xylem and phloem are simple tissues.
    (1) A and B only
    (2) B and C only
    (3) B, C and D only
    (4) C and D onlyAnswer: (2). A is false: ground tissue excludes the epidermis. D is false: xylem and phloem are complex tissues.
  6. Which statement about guard cells is NOT correct?
    (1) They possess chloroplasts
    (2) Their inner walls are thin
    (3) They enclose the stomatal pore
    (4) They regulate the opening and closing of stomataAnswer: (2). The inner walls, towards the pore, are highly thickened; the outer walls are thin.
  7. Arrange the tissues of a conjoint open vascular bundle from the outer side inwards. A. Xylem; B. Cambium; C. Phloem.
    (1) A, B, C
    (2) C, B, A
    (3) B, C, A
    (4) C, A, BAnswer: (2). Phloem lies on the outer side, cambium in the middle and xylem on the inner side.

Common Mistakes to Avoid

Watch out
  • Writing that roots have a cuticle. Correct: the cuticle is absent in roots.
  • Saying the outer wall of a guard cell is thick. Correct: the inner wall, towards the pore, is highly thickened.
  • Calling the guard cells of grasses bean-shaped. Correct: they are dumb-bell shaped.
  • Leaving the subsidiary cells out of the stomatal apparatus.
  • Describing root hairs as multicellular. Root hairs are unicellular; shoot trichomes are usually multicellular.
  • Counting the vascular bundles as ground tissue. Ground tissue excludes the epidermis and the vascular bundles.
  • Calling monocot vascular bundles open. They lack cambium, so they are closed.
  • Writing that radial bundles occur in stems. Correct: radial in roots; conjoint in stems and leaves.

Frequently Asked Questions

What are the three tissue systems in flowering plants?

The three tissue systems are the epidermal, the ground (fundamental) and the vascular (conducting) tissue systems. They are grouped on the basis of structure and location. The epidermal system covers the plant, the ground system forms its bulk, and the vascular system of xylem and phloem conducts water, minerals and food.

What is a stomatal apparatus?

A stomatal apparatus is the stomatal aperture together with the two guard cells and the surrounding subsidiary cells. Subsidiary cells are epidermal cells near the guard cells that sometimes become specialised in shape and size. The guard cells regulate the opening and closing of the stomatal pore.

How do the guard cells of grasses differ from those of most other plants?

In most leaves, each stoma has two bean-shaped guard cells. In grasses, the guard cells are dumb-bell shaped, with bulbous ends and a narrow middle. In both types, the inner walls facing the pore are highly thickened, the outer walls are thin, and the guard cells contain chloroplasts.

What is the difference between root hairs and trichomes?

Root hairs are unicellular elongations of root epidermal cells that absorb water and minerals from the soil. Trichomes are epidermal hairs of the stem. They are usually multicellular, branched or unbranched, soft or stiff, and sometimes secretory. Trichomes help prevent water loss due to transpiration.

What is the ground tissue system?

The ground tissue system includes all tissues except the epidermis and the vascular bundles. It is made of parenchyma, collenchyma and sclerenchyma and forms the main bulk of the plant. In stems and roots it forms the cortex, pericycle, pith and medullary rays; in leaves it forms the mesophyll.

What is the difference between open and closed vascular bundles?

An open vascular bundle has cambium between the phloem and the xylem, so it can form secondary xylem and phloem. Dicot stems have open bundles. A closed vascular bundle has no cambium and forms no secondary tissues. Monocots have closed bundles.

What is the difference between radial and conjoint vascular bundles?

In radial bundles, xylem and phloem lie in an alternate manner on different radii, as in roots. In conjoint bundles, xylem and phloem lie together on the same radius, as in stems and leaves. Conjoint bundles usually have the phloem only on the outer side of the xylem.

Which points from the tissue system are most important for NEET?

NEET mostly asks the NCERT points on stomata, guard cell walls, the stomatal apparatus and vascular bundle types. Learn bean-shaped versus dumb-bell shaped guard cells, which wall is thickened, where the cuticle is absent, and the open, closed, radial and conjoint bundles with their locations.

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