Biology tissues class 9

BIOLOGY-
PLANT TISSUES
BY
S.DHANESWAR
A PRESENTATION BY DHANESWAR.S IX AVJC 1

TISSUES
• A group of cells which are similar in Origin, Structure And Functions are
called tissues.
• Tissues are classified as
• Meristematic Tissues and
• Permanent Tissues in plants.

MERISTEMATIC TISSUES
• The meristematic tissues are immature and divide actively.
• The term meristem was coined by K.Nageli[1858].
• They help in the Production Of New Cells and thus Promote The
Growth Of The Plant.
• They are found in Only High Vascular Plants and help in the production
of various organs.

CHARACTERS OF MERISTEMS
1. Cells are small in size and isodiametric, cuboidal or polygonal in shape.
2. Cells are arranged compactly without intercellular spaces.
3. Cell walls are thin and cellulosic.
4. Cytoplasm is dense and abundant . It shows a big conspicuous nucleus.
5. Numerous small vacuoles are found in cytoplasm.
6. Proplastids are present and ergastic substances are absent.
7. Cells divide continuously and show active metabolism.

TYPES OF MERTEMATIC TISSUES
1. Based on the origin.
2. Based on the position.
3. Based on the plane of division.

TYPES OF MERISTEMS BASED ON
ORIGIN
1. Primary meristem.
2. Secondary meristem.

PRIMARY MERISTEM
• Primary meristems are formed at the embryonic stage and continue to
remain active in the mature parts of the plant body.
• They are found in the growing tips and vascular bundles.

SECONDARY MERISTEM
• The meristems formed from permenant tissues by a process od
dedifferentiation.
• The secondary meristems helps in secondary growth of stems and roots.

TYPES OF MERISTEMS BASED ON
POSITION
1. Apical meristem.
2. Intercalary meristem.
3. Lateral meristem.

APICAL MERISTEM
• They are present at the growing tips of roots, stems, branches etc.
• They are helpful in the linear growth of the plant body.

INTERCALARY MERISTEM
• It is present at the nodes of the stem, branches and at the base of the leaf
sheath.
• They help in the linear growth of the stem and leaves.
• They are active only for a short period and gradually change into permanent
tissues.

LATERAL MERISTEM
• They are found at the lateral sides of the plant body.
• They are helpful to increase the thickness of the organs like stem and root.
• They are involved in the secondary growth and produces secondary xylem
and secondary phloem.

TYPES OF MERISTEMSBASED ON THE
PLANE OF DIVISION
1. Plate meristem.
2. Rib meristem.
3. Mass meristem.

PLATE MERISTEM
• In this type, the cells divide in anticlinal manner(perpendicular to the cell
surface) and produce a single layer of cells.

RIB MERISTEM
• In this type, the cells divide in periclinal manner(parallel to the cell surface)
and produce longitudinal rows of cells.

MASS MERISTEM
• In this type, the cells divide in all planes and produce a mass of cells.

PERMENANT TISSUES
• A group of mature cells which have lost the capacity of division either
temporarily or permanently and perform a specific function is known as
permenant tissues.
• The cells are big in size.
• A single large vacuole is present.
• The plastids are well developed.
• A small nucleus is found at one side of the cell.

CHARACTERSTICS OF PERMENANT
TISSUES
• The cells are big in size.
• A single large vacuole is present.
• The plastids are well developed.
• A small nucleus is found at one side of the cell.
• Ergastic substances are present.
• Intercellular spaces are present.
• The cells do not divide[differentiation], but if necessary they can become
meristematic[dedifferentiation].

TYPES OF PERMENANENT TISSUES
1. Simple tissues.
2. Complex tissues.
3. Special tissues.

SIMPLE TISSUES
• The group of cells which are similar in size, structure and function is called
simple tissues.

TYPES OF SIMPLE TISSUES
1. Parenchyma.
2. Collenchyma.
3. Sclerenchyma.

PARENCHYMA
• It is known as fundamental tissue or ground tissue.
• It is a soft tissue and found in the cortex of stem, root, mesophyll, petals,
fruits, seeds, phloem and pith.
• It is a living tissue.
• The cells are oval spherical or rectangular in shape with thin cell walls.
• The cells are loosely arranged with large intercellular spaces between them.

TYPES OF PARENCHYMA
1. Aerenchyma.
2. Chlorenchyma.
3. Storage parenchyma.

AERENCHYMA
• In aquatic plants large air cavities are present in parenchyma to help them
float. Such a parenchyma is called aerenchyma.

CHLORENCHYMA
• In some situations parenchyma contains chlorophyll and performs
photosynthesis. Such a parenchyma is called chlorenchyma.

STORAGE PARENCHYMA
• The parenchyma which stores food is called storage parenchyma.

COLLENCHYMA
• It is a living mechanical tissue which is found in young stems, petioles,
peduncles and around vascular bundles.
• The cells of this tissue elongated cylindrical or polygonal in shape.
• It gives flexibility in plants without breaking when it blends.
• There is very little intercellular spaces.
• The cell wall is rich in cellulose and pectin.

TYPES OF COLLENCHYMA
1. Angular collenchyma.
2. Lacunar collenchyma.
3. Lamellar collenchyma.

ANGULAR CHOLLENCHYMA
• The cells are not arranged in regular rows.
• Intercellular spaces are absent.
• It is found in the stems, selenium, datura and cucurbita.

LACUNAR CHOLLENCHYMA
• The cells are irregularly arranged.
• Small intercellular spaces are present.
• It is found in the stems of leucas.

LAMELLAR CHOLLENCHYMA
• The cells are arranged horizontal rows.
• Intercellular spaces are absent.

SCLERENCHYMA
• It is a simple mechanical tissue compose of dead cells.
• It provides strength and hardness to plant parts.
• The cells are long and narrow and thickened walls due to presence of lignin.
• As the cell walls are thick there is no internal space inside the cell.
• This tissue is present in stems in the veins of leaves, around vascular bundles
and the hard covering seeds and nets.

TYPES OF SCLERENCHYMA
1. Fibres.
2. Sclereids.

FIBRES
• The cells are elongated with the tapering ends.
• They are found in the cortex and around vascular bundles.

SCHLEREIDS
• The cells are different shape and size.
• The cell walls are very thick due to the deposition of lignin.
• Sclereids are found in fleshy fruits, roots, leaves and seeds.

COMPLEX TISSUES
• The group of dissimilar cells which coordinate to perform a common
function is known as complex tissues.

TYPES OF COMPLEX TISSUES
1. Xylem.
2. Phloem.

XYLEM
• The term xylem was coined by k.nageli[1858].
• It is a complex tissue that conducts water and dissolved mineral salts from
root to the aerial parts of the plant body.
• Tracheid and vessels are tubular structure which helps to transport water and
minerals vertically.
• The xylem parenchyma stores food.
• The xylem fibres are supportive in function.

TYPES OF XYLEM
1. Xylem parenchyma.
2. Xylem fibres.
3. Vessels.
4. Tracheid.

PHLOEM
• The term phloem was coined by k.nageli[1858].
• It is a complex tissue that conducts organic solutes from the leaves to the
other parts of the plant body.
• Sieve tubes are tubular cells with perforated walls.
• Expect phloem fibres other phloem cells are living cells.[only phloem fibres
are dead cells]

TYPES OF PHLOEM
1. Phloem parenchyma.
2. Phloem fibres.
3. Companion cells.
4. Sieve cells.
5. Sieve tubes.

SPECIAL TISSUES
• The group of cells which is composed of secretary cells located in various
parts of the plant body is called special tissues.

TYPES OF SPECIAL TISSUES
• Digestive glands.
• Nectar glands.
• Osmophors.
• Secretory cavities.
• Hydathodes.
• Lactiferous tissue.

THANK YOU

Biology tissues class 9

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