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Leaf structures

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					Lesson Plan
 BIOLOGY
  Std. -XI
          Concept

Study of the Leaf structure &
Phyllotaxy in plants.
                  Purpose
Awareness about the
 structure of a typical
 leaf & the types of
 Phyllotaxy in plants for
 their mode of
 arrangement
              Category & Time
   Medium
   40-45 minutes
          Learning Outcomes
Student’s awareness about
  the –
* Typical leaf structure
* Essentiality of various
  leaf parts in a plant
* Familiarity about
  Phyllotaxy in plants
Lesson flow                  Technica NonTehn Teache Student
                               l        -ical   r



Why                             -    Verbal Active Partly
To have an idea about                  com           active
   the importance                      muni
of leaf parts in a typical             catio
   leaf.
                                       n
To catagorise the plants
   on the basis of
phyllotaxy,
What                       Tech.     Non        Teacher Student
                                     Tech.
                           Module on Original   Active   Active
Definition of Leaf     M   Bhartiyavi leaf
Parts of typicalLeaf   M   dya        Specimens
Importance of these    M
parts
Definition of          M
Phyllotaxy
Types & subtypes of    H
Phyllotaxy
How                         Tech. Non Tech. Teacher Student

Activity:                    Q/A on    Leaf           Active        Active
Session of Q/A on leaf       monitor      specimens      through
   structure & Phyllotaxy                             explanation
Study the structure of Leaf
   through original
   specimens.
Look at the venation in leaf
   specimens & study it.
                 Question session
Q. Give the definition of leaf.
Q. What do you call the structure by which leaf is attached at
  plant?
Q. Give the technical term for the mode of arrangement of
  leaves on plant.
Q. How many types of arrangement of leaves in plants are
  there/
What Else                         Tech. NonTechni- Teacher Student
                                           cal
1. Collect some more leaf            -  Collection of Passive Active
    specimens                           leaves samples
to identify their venation,
    from your
neighboring area .
2. Categories different plant
    as monocot
& dicot on the basis of
    venation.
3. Find out that all the leaves
    have all
the three parts or not. If not,
    note down
the missing parts.
                  Definition of Leaf
Leaf is the flattened outgrowth of Stem or a branch that
develops at node & has a bud in it’s axil. These are the
dissimilar organs & are meant primarily for Photosynthesis,
Respiration & Transpiration.
           Parts of the Leaf

       1. Leaf Base2. Petiole3. Lamina




more
                    Leaf Base
The part of leaf attached to the stem or branch is
called- Leaf base. It protects a Bud in it’s axil.
                         Petiole
The part of leaf that connects the lamina with stem, is called leaf
petiole. Some time a leaf may not have a petiole, such leaves are
called – Sessile otherwise the leaf is called Petiolate.
                          Lamina
It is the flat, expended & broad part of leaf with framework of veins
& veinlets. The lamina is the most important part of the leaf as it is
the seat of food manufacturing in plant.
                       Phyllotaxy

It is the mode of arrangement / distribution of leaves on stem or it’s
                               branch.
  Phyllotxy ensures that leaves may receive maximum sunlight for
                           photosynthesis.


                             Phyllotaxy

                 Alternate    Opposite    Whorled
            Alternate Phyllotaxy

In such case only one leaf is attached at each node. The leaves
are so arranged that a line drawn on the stem through the leaf
bases will take a spiral course. Ex. Hibiscus, Brassica etc.
            Opposite Phyllotaxy


   In such case two leaves are present at each node,
standing opposite to each other. It is of two subtypes -

                 Opposite decussate
                 Opposite superposed
               Opposite Decussate

Here pairs of leaves at each successive node are placed
at right angle to each other. Eg. Ocimum, Calotropis
etc.
              Oposite Superposed

Here pairs of leaves at each successive node are
placed over each other in same plane.
Eg.Eugenia,Quisqualis etc.
                        Whorled Phyllotaxy

In this type more than two leaves are present at each
node, forming a whorl. Ex. Oleander, Alstonia etc.




http://www.umanitoba.ca/faculties/science/biological_sciences/lab10/biolab10_4.h
tml#Structure
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