Chapter-8
Tissue and Tissue System
Contents
Meristematic Tissue and its classification
Permanent Tissue and its classification
3 types of Tissue systems
Different types of vascular bundles
Internal structure of Monocot root and stem
Primary internal structure of Dicot stem
What is plant tissue ?
Multicellular organisms are made up of millions of cells. Cells are structural and functional units of life. They show divisions of labour and each cell performs a particular function
efficiently. Such cells are grouped together and are referred to as tissues.
Plant tissue is a group of cells which are similar in structure and origin and perform a similar 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 flowers ,leaves,
stems and roots.
Classification of plant tissue
A group of cells Tissue A group of tissue Tissue System A group of tissue system Organ A group of organs Plant body
Based on position, structure and function plant tissues are of two types:
1.Meristematic tissue 2.Permanent tissue
What is meant by permanent tissue ?
These are matured meristematic tissue.
The meristematic cells form permanent tissue once they lose the ability to
divide. Thus, the cells of a tissue which are incapable of cell division is called permanent tissue. These cells have a definite shape,size and function and may be dead or living. They cannot divide without any special condition.
The process by which cells arise from meristematic tissue and take up a
permanent shape,size and function is
called differentiation. Fig: Simple Permanent Tissue
Parenchyma Collenchyma Sclerenchyma
Properties of permanent tissue
• The cells of permanent tissue are incapable of division.
• The permanent tissues may be living or dead.
• Cell wall is thick and ornamented.
• The content of protoplasm of the cells is comparatively less.
• No protoplasm is seen in the dead cells.
• They possess comparatively smaller nucleus.
• They have big vacuoles.
• Intercellular space is seen.
• The cells are completely developed and attained full size and shape.
Difference between Meristematic and Permanent tissue
Meristematic Tissues Permanent Tissues
Continuously dividing cells Generally incapable of cell division Cells are small and isodiametric Variable in shape and size
Cell wall is thin Cell wall is thick
Nuclei are large Nuclei are small
Vacuoles are absent Vacuoles are present
Intercellular spaces absent Intercellular spaces present
Metabolic activities are high rate Metabolic activities are low rate Inorganic inclusion absent Inorganic inclusion present
Cells are undifferentiated Cells are differentiated
Simple tissue Simple or complex tissue
Classification of plant tissue in a tabular form
1. Sclereid 2. Fibre
Permanent Tissue
Simple Permanent Tissue
Complex Permanent Tissue
Secretory Tissue 1. Parenchyma
2. Collenchyma 3. Sclerenchyma
1. Xylem 2. Phloem
1. Laticiferous tissue 2. Glandular
1. Xylem Fibre 2. Phloem Fibre
1. Aerenchyma 2. Chlorenchyma
Simple permanent tissues : The permanent tissues which are composed of similar cells in shape, size and structure are known as Simple permanent tissue.
Simple Permanent Tissues
Parenchyma Collenchyma Sclerenchyma
1. Palisade 2. Spongy
1. Sclereid 2. Fibre
Features Parenchyma Collenchyma Sclerenchyma
1. Cell Type Isodiametric cells which are oval, spherical or polygonal in shape
Elongated, oval or polyhedral in shape.
Variable in shape. Fibres and sclereids.
2. Cell Wall Thin cellulosic cell wall. Uneven thickening on their cell wall. Lignified secondary cell wall present.
3. Cytoplasm Abundant. Present. In mature cell it is absent.
4. Nucleus Present (Living tissue) Present (Living tissue) Absent (Dead tissue)
5. Vacuoles Large vacuole Vacuolated Absent
6. Intercellular spaces
Present Absent Absent
7. Occurrence Basically packing tissue. All soft part of plant, Pith, Cortex,
medullary rays
Dicot stems, petiole and beneath the epidermis. Absent in monocot and roots
Dicot hypodermis, bundle sheath, pericycle, seed and fruit shell.
8. Functions Organizes the plant body, food storage, photosynthesis
Provides mechanical support and rigidity, photosynthesis
Mechanical support and rigidity, conduction
Complex Permanent Tissue : The permanent tissue which is composed of more than one type of cells is known as complex tissue .
Complex Permanent Tissues
Xylem Phloem
Components
1. Tracheid 2. Vessel
3. Xylem parenchyma
4. Xylem fibre Components
1. Sieve tube element 2. Companion cell
3. Phloem parenchyma 4. Phloem fibre
Difference between xylem and phloem
XYLEM PHLOEM
Conducts water and minerals . Conducts food .
Conduction takes place in one direction . Occurs in 2 directions – upward and downward . Conducting channels are tracheids and vessels . Conducting channels are sieve tubes .
Only xylem parenchyma is living, all other
elements( tracheid, vessel and fibre ) are dead
All elements(sieve tube,companion cell,phloem parenchyma) are living only the fibres are dead . Xylem conducts and gives mechanical strength
also due to presence of lignified vessels
Phloem conducts, gives no mechanical strength
Xylem vessel Phloem vessel Water and food
Cells have end walls with perforations
Two way flow One way only
Water and minerals
Thick walls
stiffened with lignin No end walls between cells
Primary and Secondary growth of woody dicotyledon
Stem apical meristem
Root apical meristem
Primary meristems Mature Primary tissues Lateral meristems Secondary tissues
Protoderm
Ground meristem Procambium
Epidermis Pith
Cortex
Primary xylem
Primary phloem Vascular cambium Cork cambium
Cork
Phelloderm
Secondary phloem Secondary xylem Protoderm
Procambium
Epidermis Pith
Cortex Vascular
Cylinder Vascular cambium
Cork cambium
Cork
Phelloderm
Secondary phloem Secondary xylem Primary phloem
Primary xylem Pericycle
Ground meristem
In vascular plants, such as angiosperms and gymnosperms, cell division takes place almost exclusively in specific tissues known as meristems.
Apical meristems, which are located at the tips of shoots and roots in all vascular plants, give rise to three types of primary meristems, which in turn produce the mature primary tissues of the plant.
The three kinds of mature tissues are dermal, vascular, and ground tissues.
Primary and Secondary growth of woody dicotyledon
The two populations of dividing cells unite to form a continuous ring of dividing cells, the vascular cambium.
Primary dermal tissues, called epidermis, make up the outer layer of all plant organs (e.g., stems, roots, leaves, flowers). They help prevent excess water loss and attack by insects and microorganisms.
The vascular tissues are of two kinds: water-transporting xylem and food- transporting phloem.
Primary xylem and phloem are arranged in vascular bundles that run the length of the plant from roots to leaves.
The ground tissues, which comprise the remaining plant matter, include various support, storage, and photosynthetic tissues.
Primary and Secondary growth of woody dicotyledon
Secondary, or lateral, meristems, which are found in all woody plants and in some herbaceous ones, consist of the vascular cambium and the cork cambium. They produce secondary tissues from a ring of vascular cambium in stems and roots.
Primary and Secondary growth of woody dicotyledon
Fig: Secondary growth of dicot stem
Secondary phloem forms along the outer edge of the cambium ring, and secondary xylem (i.e., wood) forms along the inner edge of the cambium ring. The cork cambium produces a secondary dermal tissue (periderm) that replaces the epidermis along
older stems and roots.
Primary and Secondary growth of woody dicotyledon
Fig: Secondary growth of dicot stem
THANK YOU
H.W.
1. What is periderm ?
2. What is meant by cork cambium and vascular cambium ?
3. Learn the properties of permanent tissue.
4. Differentiate the meristematic tissue with permanent tissue.
5. Learn the complex permanent tissue.
