2. Tissue is a cellular organizational
level intermediate between cells and
a complete organism. Hence, a tissue
is an ensemble of cells, not necessarily
identical, but from the same origin,
that together carry out a specific
function.

3. The study of tissue is
known as histology or, in
connection with disease,
histopathology.

4. Plant Tissues
Permanent Tissues
Meristimatic Tissues (Cells with speciallised structure and function that have lost their
(These cells continuously divide throughout the life of the plant) ability to divide further)
Simple Permanent Tissue
Apical Meristem Complex Permanent Tissue
Parenchyma
Xylem
Lateral Meristem
Collenchyma
Phloem
Intercalary
Meristem
Sclerenchyma

5. Meristematic tissue: Cells of this tissue continue to divide
throughout the life of the plant. Some of these cells lose their
ability to divide and become part of other tissues.
Name of the Location Function
tissue
Apical Meristem Present at the growing tip of stem Increase in length of stem
and root and root
Lateral Meristem Found on the lateral sides of Increase in girth of stem
(also called roots and stem and root
cambium)
Intercalary Present at the base of leaves or Growth of leaves and
Meristem internodes branches

7. A longitudinal section through a growing shoot tip showing apical
meristematic tissue. Note that the cells are small, have dense
cytoplasm, and are very tightly packed.

8. High power view of a longitudinal
section of the Coleus apical
meristem. The apical meristem is a
dome-shaped mass of dividing cells
at the tip of the shoot. The apical
meristem will produce the three
primary meristems: protoderm,
procambium, and ground
meristem. These three meristems
in turn will produce new cells that
will differentiate into the
epidermis, primary vascular
tissues, and ground tissues (pith
and cortex).

9. A longitudinal section through a root tip. The meristematic tissue is
located just above the root cap. This too is apical meristem; division
of these cells followed by cell elongation results in the root growing
in length.

10. It is a cross section of a dicot
stem.
Focus on the two large
vascular bundles in the center
of the slide.
The xylem tissue is stained
red.
Just above the xylem is a
layer of meristematic tissue,
the vascular cambium.
The phloem tissue is found
outside of the vascular
cambium.

11. This is a high-power view of a cross-section showing a lateral meristem, the vascular cambium, in the
same plant shown in previous slide. Again, the xylem tissue is stained red, and the large cells on the top
of the slide are phloem. The green brick-like cells between the xylem and phloem is the area in which
the vascular cambium is located. The new cells produced by the cambium are initially like those of the
cambium itself, but, as they grow and mature, their characteristics slowly change as they differentiate
into other tissues. The vascular cambium is a single layer of cells within this brick like region; it is
responsible for the growth in diameter of a stem. The tissues produced by the vascular cambium are
secondary tissues.

12. Permanent tissue: Cells of this tissue have lost their ability to
divide and they have a specialized structure to perform
specific functions.
Based on the type of cells present in the tissue, the
Permanent tissue is divided into two categories:
Simple Permanent Tissue
and
Complex Permanent Tissue.
While the simple permanent tissue consist of only one type
of cells (eg. Parenchyma),
the complex permanent tissue consists of more than one
type of cells (eg. Xylem and phloem)

13. S i m p l e P e r m a n e n t T i s s u e s
Parenchyma
Structure:It is the fundamental tissue composed of thin walled, living
cells whose cell wall is composed of cellulose. Small intercellular spaces
are present between the cells.
Location and function: It occurs in all soft parts of plants and is
meant for storage of food and to provide turgidity to softer parts of plants.
Parenchyma tissue in stem and roots store nutrients and water.
Types of parenchyma:
i) Chlorenchyma :Certain parenchymatous tissue contain chloroplast
and synthesize food by the process of photosynthesis.
ii) Aerenchyma: In aquatic plants parenchymatous cells have air cavities
between them to store air, such a tissue is called Aerenchyma. It provides
buoyancy to the aquatic plants so that they can float in water.

15. Collenchyma
Structure: This tissue is composed of somewhat elongated cells with
cell walls that are irregularly thickened at corners due to deposition of
cellulose or pectin. They may be oval, circular or polygonal. Very little
intercellular spaces are present.
Location: It occurs below the epidermis of stem and petiole (stalk of
the leaf) and around veins.
Function: This tissue provides mechanical support and flexibility and
in some cases it may possess chloroplasts to perform Photosynthesis.
The stem and leaves are able to bend easily and then come back to
their original position due to the presence of collenchyma.

16. Collenchyma in Transverse Section Showing
Wall Thickenings
1. Cell Wall
2. Wall Thickenings
3. Protoplasm
4. Vacuole

17. Sclerenchyma
Structure: It is a tissue of dead and thick walled cells, having no
intercellular spaces. The thickenings are of cellulose or lignin or both.
Several unlignified areas called pits often develop on walls.
Location: This tissue is usually found in the hard and stiff parts of the
plant like seed coat, husk of coconut, in the stem around vascular
bundles, veins of leaves and hard covering of fruits and nuts.
Function: It is the chief mechanical tissue in plants and is able to bear
push, pull, strain and shearing forces. It provides strength to plant parts
and also protects the delicate parts of the plants.
They are of two types: fibres and sclereids.

18. Sclerenchyma

21. Epidermis and Bark
The protective tissues
The epidermis usually consists of a single-layered group of cells that covers
plants leaves, flowers, roots and stems. It forms a boundary between the plant
and the external world.
Bark is formed from the meristem that appears later in the life cycle of a plant.
Woody stems and some other stem structures produce a secondary covering
called the secondary meristem or periderm or cork cambium that replaces the
epidermis as the protective covering.
The periderm replaces the epidermis, and acts as a protective covering like the
epidermis.
Cells produced on the outside by periderm form the cork. Cells of have suberin
in their walls to protect the stem from drying and pathogen attack. Older cork
cells are dead, as is the case with woody stems. As the stem grows, the cork
cambium produces new layers of cork which are impermeable to gases and
water.

24. A high-power view of one glandular hair. Secretory hairs may
provide a chemical defense against insects.

26. Another type of surface tissue, the outer bark or periderm (stained red in this slide).
Periderm is found on the surface of woody plants; it includes the cork cells on the
surface of older woody stems. The periderm replaces the epidermis in plants that have
secondary growth. The cork cells are dead; it is their waterproofed cell walls that
function as the protective outer covering of plants. Meristematic cells within the
periderm (cork cambium, the other lateral meristem) produce the cork cells.

27. Complex Permanent Tissues
Xylem and Phloem

28. Xylem
It is a complex permanent
tissue, which is specialized
for the conduction of water
and mineral substances in
the plant body. Xylem is a
heterogenous tissue made
up of four different types of
cellular elements.
They are:
•Xylem tracheids
•Xylem tracheae or vessels
•Xylem fibers and
•Xylem parenchyma

29. Phloem:
Phloem is a complex
permanent tissue, which is
specialized for the
conduction of food and
other organic substances.
Phloem is also a
heterogenous tissue, made
up of four different types of
cellular elements, namely,
•Sieve tubes
•Companion cells
•Phloem parenchyma and
•Phloem fibres