Plant Tissues (class 9th)

Tissue is a group of cells having similar origin, structure and function. For example- Parenchyma ,Collenchyma etc.

Features of Plant tissue –

• Most of the plant parts are tissues with dead cells because tissues provide mechanical strength to the plant.

• Cells of some tissues are live.

•In plants ,growth takes place in some parts, so these parts contains tissue having continuously dividing cells.

Plant tissues are of two types –  Meristematic tissue and Permanent Tissue

        Meristematic Tissue  

Meristematic tissues are found in the growing regions of the plant . For ex- Root tip & Stem tip. Cells of this tissue tend to divide continuously.

These tissues are of three types-

Apical Meristematic tissue- These tissues are present in the tips of stems and roots.  They help in the growth of stems and roots.

 Lateral Meristematic tissues- These tissues are present in in the sides of stems and  roots. For ex- Cambium in stem and root. They help to increase the girth of the stems and roots.

Intercalary meristematic tissues- These are present at the base of leaves and     internodes. These help in growth of branches and leaves.

         Permanent tissue

Permanent tissues are formed from meristematic tissues. They do not divide and have permanent shape and size.

These are of two types- Simple  Permanent Tissue and Complex Tissue

Simple Permanent Tissue -These tissues are made of single type of cells. Ex- Parenchyma ,Arenchyma And  Sclerenchyma .

                                                                

            Parenchyma

Tissue has loosely packed thin walled cells. Inter-cellular space is found .

Parenchyma 

Chlorenchyma -Some parenchyma contain chlorophyll i.e.  Chlorenchyma of leaves, involve in Photosynthesis.

Chlorenchyma 

Aerenchyma -Some parenchyma contain large air cavities i.e. Aerenchyma of hydrophytes help the plant to float on water.

Aerenchyma

       Collenchyma

•      This tissue is composed of elongated cells with less inter-cellular space.

•      The cell walls of cells are thicker at corner due to presence of lignin.

•      This tissue gives flexibility to the parts of plant and allow easy bending.

•      This tissue also provide mechanical support to the small parts of plants

     Sclerenchyma

•      This tissue is composed of long narrow dead thick walled cells.

•      The cell wall contains lignin  which provide hardness to them.

•      No intercellular space is there in sclerenchyma.

•      This tissue provide hardness and strength to the parts of plant like wall of  Wall-nut, seed coat etc.

Complex Tissue - These tissue are made up of more than one type  of cells.

                               There are two types of  complex tissues-

    Xylem -Xylem consists of   Tracheids,    Vessels     Xylem parenchyma   and  Xylem                     fibres.   The tracheids and vessels help to transport water and minerals from                          roots      to all part of the plant. Xylem parenchyma stores food and fibres help in      support.

Phloem -  Phloem consists of -sieve tubes, companion cells, phloem parenchyma and   phloem fibres.  The sieve tubes and companion cells transports food from  leaves to all parts of the plant.  Phloem parenchyma stores food and fibres    help in support.