Morphology of Flowering Plants Class 11 Science Notes Download in PDF-1(THE ROOT),CBSE

Introduction 

• Flowering plants are multicellular organisms.

• They grow by cell division

• There morphological features and traits depends upon their genetic constitution.

• In spite of showing such a diversity in external structures, all the angiosperm plants are characterized by presence of roots, stems, leaves, flowers and fruits.

• Morphology is the study of different forms of plant organs such as roots, stem, leaves, fruits, flowers, seeds, etc.

• The role of morphology is very important in the classification of plants.

• In this unit we shall learn about different morphological features of plants, how different parts of plants are modified according to their particular needs which also includes defence from their enemies.

• In this unit economic importance of some selected families of plants will also be discussed.

MORPHOLOGY OF FLOWERING PLANTS: PARTS OF A  FLOWERING PARTS

Morphology of Flowering Plants Class 11 Science Notes - ROOTS

• It is a non-green, underground and cylindrical part of the plant.
• It generally grows downwards into the soil i.e., it is the descending part of the plant axis.
• Roots lack nodes, internodes, leaves but leads to the formation of endogenous growth of lateral branches.
• Roots are positively geotropic and negatively phototropic i.e., roots grow in the direction of gravity (geotropism) but its growth is opposite to the sun or source of light (phototropism).

The root system in plants are well developed. The main root and its lateral branches forms the root systems of the plant.

There are three types of root system-

      1)    Tap root system-

The primary root is directly elongated from the radicle and grows inside the soil (e.g., dicots).

It bears lateral roots of several order.

This order can be secondary, tertiary roots, etc.

The tap root system is constituted by the primary roots and its lateral branches.

MORPHOLOGY OF FLOWERING OF PLANTS: TAP ROOT SYSTEM

 2) Fibrous root system-

In monocotyledonous roots, the primary root is very short lived.

The primary root is replaced by numerous fine fibrous roots.

Fibrous roots originates from the base of the stem.

These fine fibrous roots constitute the tap root system.

It is seen in wheat plant.

MORPHOLOGY OF FLOWERING PLANTS : FIBROUS ROOT SYSTEM

       3)     Adventitious root system-

Adventitious roots develops from other parts of the plant other than the radicle.

e.g., grass, monstera and banyan tree.

MORPHOLOGY OF FLOWERING PLANTS : ADVENTITIOUS ROOT SYSTEM

Main functions of roots-

1.      Roots helps in absorption of water and minerals from the soil.

2.      Roots provide anchorage to the whole plant body.

3.      Roots helps in the storage of reserve food materials.

4.      Roots are also the sites for synthesis of plant growth regulators.

Regions of the root

MORPHOLOGY OF FLOWERING PLANTS: REGIONS OF ROOT TIPS

  

  1.      Root cap – it is a thimble like structure which covers the apex of the root. Root cap is multicellular in nature is composed of parenchymatous cells. It protects the apex of the of the root as it makes way through the soil.

  2.      Region of meristematic activity - this region is found few milimetres above the root cap. The constituent cells of this region are thin walled, small and have dense protoplasm. These cells divide repeated to further produce more new cells.

  3.      Region of elongation - these region lies just above the region of meristematic activity. The constituent cells of this region are responsible for grow and enlargement of roots in length.

  4.      Region of maturation - the cells of zone of elongation which mature and differentiate become the part of zone of maturation. Some epidermal cells of the region of maturation forms very fine and delicate thread like structures called root hair. Root hairs helps in increasing the surface area for absorption of water and minerals from the soil.


Modifications of root

   In order to perform certain functions like respiration, storage, protection and to provide support, roots undergo various modifications in their shape and structure.

   Storage roots- primary tap root modifies to store food. e.g., tap roots of carrot, turnip and adventitious roots of sweet potato gets swollen to store food.

STORAGE ROOTS- TAP ROOT OF CARROT AND TURNIP AND ADVENTITIOUS ROOT OF SWEET POTATO

   Prop roots- arises from branches to provide mechanical support to heavy branches like pillars. e.g., banyan tree.

               PROP ROOTS OF BANYAN TREES: MODIFICATION OF ROOTS FOR SUPPORT

   Stilt roots- They arise from lower nodes of stem to support main axis and enter the soil obliquely e.g., sugarcane, maize.

                        STILT ROOTS OF MAIZE : MODIFICATION OF ROOTS  FOR SUPPORT.

   Respiratory roots- in some plants such as Rhizophora growing in swampy areas, many roots come out of the ground and grows vertically upwards to get oxygen for respiration. Such roots are called as pneumatophores.

                                RESPIRATORY ROOTS , PNEUMATOPHORE OF RHIZOPHORA 

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