TISSUES IN FLOWERING PLANT (ANATOMY)

 

    

INTRODUCTION:-

·         Study of internal structure of organisms is called anatomy.

The Tissue:-

·         Tissue is the group of cells having common origin and common function.

·         It is of two types:-

1.       Meristematic Tissu

2.    Permanent Tissue

Meristematic Tissue:-

·         The tissues whose cells having tendency to take part in cell division. This tissue is responsible for growth of plant.

·         It is are of three types:-

1.       Apical Meristem

2.       Intercalary Meristem

3.       Lateral Meristem

1.      Apical Meristem: - Occurs at the tips of roots & Shoots and are of Primary Meristem. It is responsible for increase in length length of plant.

                                                                                                                         

2.      Intercalary Meristem:- Occurs between the mature tissue and are of Primary Meristem. It is responsible for formation of branch of flower.

3.      Lateral Meristem:- Occurs in mature region of root and shoot and are of Secondary Meristem. It is responsible for Secondary growth. It activated after primary growth.

Auxiliary bud: - The buds which are present in the axils of leaves and are responsible for formation of branches or flowers in plants.

Fig- Type of meristem based on their position.

Permanent Tissue:-

·         The tissue whose cells lose their tendency to take part in cell division. It is formed in last division of primary and secondary meristem.

·         It is are of three types:-

1.      Simple tissue

2.      Complex tissue

1.      Simple Tissue:- It is made up of only one type of cells. It is also of three types

1.      Parenchyma

2.      Collenchyma

3.      Sclerenchyma

Ø  Parenchyma:- It is major component in the organ of plant. It is made up of isodiametric cells having thin cell wall of cellulose. It arranged with small intracellular spaces. It perform various functions as Photosynthesis, Storage and Secretion .

Ø  Collenchyma:- It is formed below the epidermis in dicotyledonous plant. It is made up of cells which are much thickened at corner due to deposition of cellulose, hemicellulose and pectin. Its arrangement is compacted i.e. don’t have any intracellular spaces. It also performs to give mechanical support to the plant. e.g. -Young Stem, Petiole of leaf etc.

Ø  Sclerenchyma:- It is made up of long, narrow dead-cells of thick and lignified cell wall having few numerous pits. It is of who types-

1)      Fibres:- It found in various part of plant body and made up of thick walled, elongated and pointed cells.

2)      Sclereids:- It is made up of oval, spherical and cylindrical thick cells with a lot of cavities (lumen). It is found in wall of nuts, pulp of fruits (guava, pear etc.) , seed coat of legumes and leaves of tea. It also provides mechanical support.

2.      Complex Tissue:-It consists of more than one type of cells which work together as a unit. It is of two types.

1.      Xylem

2.      Phloem

Ø  Xylem:- It functions in conduction of water and minerals from roots to stem and leaves. It also provides mechanical strength. It also consist of four type of elements

1)      Tracheids: - It is elongated or tube like cell of thick and lignified cell wall and tapering end. It helps in transporting water and minerals from roots to stems and leaves.

2)      Vessels:- It is cylindrical tube like cells of lignified cell wall and large central cavity called vessel members. It also help in transporting water and minerals from roots to stems and leaves.  

3)      Xylem fibres:- It is nonliving Sclerenchyma cell of highly thickened cell wall. It is present between tracheids and vessels. It gives mechanical support to xylem. 

4)      Xylem Parenchyma:- It is cells of thin cell wall made of cellulose. It performs a function to store food materials as starch and cellulose and also some other substances as tannin. It also perform radial conduction of water.

·         Primary xylem is of two types:-

                                                         I.            Protoxylem:- First formed primary xylem is called Protoxylem.

                                                       II.            Metaxylem:- Later formed primary xylem is called Metaxylem.

(Note-In stems occur endarch and Roots occur exarch)

Endarch-Protoxylem lies toward centre or pith and Metaxylem lies toward periphery.

Exarch- Metaxylem lies toward centre and Protoxylem lies toward periphery.

Fig-Type of Permanent tissue[Xylem a and Phloem]

Ø  Phloem:- It functions to transport the food materials generally from leaves to other parts of  plants. It also composed of followings:-

1)      Sieve tube elements:- It is long tube like structure which arrange longitudinally and associated with companion cells. A mature sieve tube aliment posses peripheral cytoplasm but lack in nucleus i.e. its function is controlled by nucleus of companion cell. 

2)      Companion cells:- It is a specialized parenchymatous cell which loosely associated with sieve tube elements. Both are connected to each other through pit field. It functions to maintain pressure gradient in the sieve tube cell   

3)      Phloem Parenchyma:-It is consist of elongated, tapering and cylindrical cells of cellulosic cell wall having nucleus and dense cytoplasm. Each cell connected to each other with pits. It functions to store food material and other components as resins, latex and mucilage.

4)      4)      Phloem Parenchyma:- It consists of sclerenchymatous cells of thick cell wall. The fibre is much elongated, unbranched and needle like apices. At maturity it loses its protoplasm and become dead. It generally absent in primary phloem i.e. found in secondary phloem.

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