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
Why
To have an idea about
the importance
of leaf parts in a typical
leaf.
To catagorise the plants
on the basis of
phyllotaxy,
Technica NonTehn Teache Student
l
-ical
r
-
Verbal Active Partly
com
active
muni
catio
n
Tech.
What
Definition of Leaf
M
Parts of typicalLeaf
M
Importance of these
parts
M
Definition of
Phyllotaxy
M
Types & subtypes of
Phyllotaxy
H
Non
Tech.
Teacher Student
Module on Original
Active
Bhartiyavi leaf
dya
Specimens
Active
How
Tech. Non Tech. Teacher Student
Activity:
Q/A on
Session of Q/A on leaf
monitor
structure & Phyllotaxy
Study the structure of Leaf
through original
specimens.
Look at the venation in leaf
specimens & study it.
Leaf
specimens
Active
through
explanation
Active
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
1. Collect some more leaf
specimens
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.
Tech. NonTechni- Teacher Student
cal
Collection of
Passive
Active
leaves samples
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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