Plant tissues are specialized collections of cells that perform specific functions. There are two main types of plant tissues: meristematic tissues and permanent tissues. Meristematic tissues are undifferentiated tissues responsible for growth, consisting of apical, intercalary, and lateral meristems. Permanent tissues are differentiated tissues, which can be living or dead, and include simple tissues like parenchyma, collenchyma, and sclerenchyma, as well as complex tissues like xylem and phloem. Each tissue type has a distinct structure and role in plant structure and function.

1. Plant tissues
Plant tissue is a collection of similar cells performing an organized function for the
plant. Each plant tissue is specialized for a unique purpose, and can be combined with
other tissues to create organs such as leaves, flowers, stems and roots.

2. Tissues types
Plant tissues
Meristematic
tissues
Permeant
Tissues
Apical
meristem Intercalary
meristem
Lateral
meristem
Simple
tissues
Complex
tissues
Parenchyma Collenchyma sclerenchyma
Xylem
Phloem
Aerenchyma Chlorenchyma Fibers Sclerids

3. Plant tissues
 Meristematic tissues:
There are some specialized cells in plants that are not differentiated and help in the growth
of the plants. These cells in a plant can be young and have the ability
to divide continuously. There is a special name for these cells, which are called the meristem
cells. The tissue that these meristem cells form in plants is called as the meristematic tissue.
Meristematic cells are all living cells. The meristematic cells can be oval or rounded
or polygonal in shape. They have a large nucleus with no vacuoles. Intercellular space
between cells is absent. The cells are also small in size but have a high capacity of cell
division.
Meristematic tissue or meristems, as they are also called are tissues that have the ability to
enlarge, stretch and differentiate into other types of cells as they mature. The cells of this
tissue are generally young and immature, with the power of continuous division.

4. Permanent tissues
 These are tissues composed of meristematic tissues when they are differentiated (in
which growth has ceased) which may be living or dead and thin or thick walled.

5. Classification of meristem
 The meristems are classified on the basis of their position in plant body into following
types
 Apical meristem: Meristem present in the apices or tips of main and lateral roots and
shoots.
 Intercalary meristem: The meristems which are found between mature tissues e.g. In the
bases of internodes of grasses. The intercalary meristems help in increasing the length of
the internode.
 Lateral meristem: The meristem situated parallel to the circumference of the organ in
which they are found. The examples are vascular cambium. These meristems help in
increasing the thickness of the plants.

7. Classification of Permanent tissues
 Epidermis
 There are several basic forms of plant tissue, formed from mostly identical types of
cells. The first is the epidermis. The epidermis in plants serves the same function as
it does in animals. It is a plant tissue formed of thin and densely packed cells,
meant to separate the inside of the organisms from the outside. The epidermis is
often covered in a layer of waxy protection, to stop the plant from burning or
drying out in the sun. The epidermis also contains guard cells, which operate small
opening called stoma. These stoma control the passage of air and water through
the leaves, allowing plants to move water and nutrients up from the soil.
 Sometimes, another form of simple plant tissues covers the epidermis, cork. Cork is
a plant tissue seen in woody plants, which dies and becomes an outer layer of bark.
This tissue is also soaked with a special waxy substance which protects against
insects, the sun, and the elements.

8. Parenchyma
 As you turn inside the plants, the next plant tissue is parenchyma. This tissue is
comprised of thin-walled cells with very large central vacuoles. The turgor
pressure of these vacuoles is elevated when they are full of water, which gives
structure and support to the plant. Parenchyma plant tissue is found in all parts of
the plant, and makes up large portions of the leaves, stems and roots. In the leaves,
parenchyma plant tissue is highly involved in the process of photosynthesis. All
parenchyma plant tissue is living, and carries out functions continually. Parenchyma
tissue, when wounded, can revert back into meristematic plant tissue to regrow
damaged areas.
 Aerenchyma is a spongy tissue that forms spaces or air channels in the leaves,
stems and roots of some plants, which allows exchange of gases between the
shoot and the root.
 chlorenchyma Parenchyma tissue that contains chloroplasts and is
photosynthetic. Chlorenchyma makes up the mesophyll tissue of plant leaves and
is also found in the stems of certain plant species.

10. Collenchyma
 Collenchyma plant tissue is similar to sclerenchyma, in that it provides support. It is
a living tissue composed of more or less elongated cells with unevenly thick,
glistening and non lignified walls. The term collenchyma is derived from Greek
word colla mean glue…which refers to thick glistening wall characteristics of
collenchyma. Often, collenchyma plant tissue is seen in young plants, with a limited
number of cells. As such, only a portion of the cell wall in these cells will be
thickened for support. This plant tissue is usually found wherever there is new
growth and the other structural cells have not set in yet.
 Collenchyma is absent in stems and leaves of those plants which develop
sclerenchyma at an early stage

11. Sclerenchyma
 sclerenchyma is a simple tissue composed of thick walled cells, often lignified,
whose function is support and sometimes protection. It is the only plant tissue
which becomes functional after its death. It is a structural tissue which dies, but
the cell wall and structure remain.
 Sclerenchyma plant tissue are of two tpes
 fibers and sclereids. These fibers can extend throughout a plant to provide
support and strength to various organs. This plant tissue is commonly found in
stems, bark, and in the hard shells of some fruits and nuts, such as pears.

13. Hard covering of nuts are made up of
sclerenchyma.

14. Tree bark is made up of sclerenchyma
tissues

15. Fibres vs Sclereids
Sclerenchyma fibres are elongated cells which
have long tapered ends and are present in most
parts of the plant.
Sclerenchyma Sclereids are cells which have a
varying shape and are distributed in the cortex,
pith, xylem, and phloem of the plants.
Cell Origin
Origin of the fibres is meristematic. Sclereids origin from mature parenchymal cells.
Shape
Fibres are elongated. Sclereids are broad and in varied shapes.
Cell Endings
Fibres have tapering ends. Sclereids have blunt ends.

17.  References
 Text book of Caravan (Principles of Botany) by Tanveer Ahmad Malik.