ANATOMY OF FLOWERING PLANTS

POINTS TO REMEMBER :

• Study of internal structure of plant is called anatomy.
• In plants cells are the basic unit.
• Cells organized into tissues and tissues organized into organs.

THE TISSUES :

• A group of cells having common origin and perform one function.
• Plant tissues are classified into two types:-
  • Meristematic tissue.
  • Permanent tissue

Meristematic tissues :

• Growth in plants is restricted to specific regions with active cell division called meristems.


• Different types of meristems are:-
  • Apical meristem:
    • Occurs in the shoot and root tips.
    • Primary meristem
    • Increase the length of plant
    
    
  • Intercalary meristem :
    • Present in-between mature tissues.
    • Primary meristem
    • Occurs in grasses and regenerate parts removed by grazing.
    
    
  • Lateral meristem:
    • Occurs in the mature regions of roots and shoots.
    • Also known as secondary meristem.
    • Responsible for producing secondary tissues.
    • Fascicular vascular cambium, interfascicular cambium and cork cambium are example of lateral meristem.
• Axillary bud :
  • During formation of leaves and elongation of stem, some cells ‘left behind’ from shoot apical meristem, constitute the axillary bud.
  • Present in the axils of leaves and are capable for forming a branch or a flower.

Permanent tissues :

• Cells produced from primary or secondary meristem stop dividing and differentiated structurally and functionally, termed as permanent cells.
• A group of permanent cell constitutes the permanent tissues.
• Permanent tissues having similar in structure and function are called simple tissues.
• Permanent tissues having many different types of cells are called complex tissues.

Simple tissues :

• Simple tissues made of only one type of cells.

Parenchyma :

• Forms major component within organs.
• Cells are isodiametric.
• Thin cell wall made of cellulose.
• Cells may be spherical, oval, round, polygonal or elongated shape.
• Cells are closely packed or have small intercellular space.
• Perform various functions such as photosynthesis, storage, secretion.

Collenchyma :

• Found either in homogeneous layer of in patches.
• Cell wall thickened in the corner due to deposition of cellulose, hemicelluloses and pectin.
• Cells are oval, spherical or polygonal in shape
• Often contain chloroplasts.
• No intercellular spaces.
• Provide mechanical support to the growing part of the plant such as young stem and petiole of a leaf.

Sclerenchyma :

• Consists of long, narrow cells
• Cell wall is thick and lignified.
• Cell wall with few or numerous pits.
• Cells are usually dead and without protoplast.
• Provides mechanical support to the organs.
• Sclerenchymas are of two types on the basis of origin, form, structure.

Fibres :

• Thick walled
• Elongated and pointed cells
• Generally occurs in group in various parts of the plant.

 

CBSE Biology (Chapter Wise) Class XI ( By Mr. Hare Krushna Giri ) 
Email Id : [email protected]