study of the leaf structure and phyllotaxy in plants

1. Lesson PlanLesson Plan
BIOLOGYBIOLOGY
Std. -XStd. -XII

2. Concept
Study of the Leaf structure &
Phyllotaxy in plants.

3. PurposePurpose
Awareness about theAwareness about the
structure of a typicalstructure of a typical
leaf & the types ofleaf & the types of
Phyllotaxy in plants forPhyllotaxy in plants for
their mode oftheir mode of
arrangementarrangement

4. CategoryCategory & Time& Time
 MediumMedium
 40-45 minutes40-45 minutes

5. Learning OutcomesLearning Outcomes
Student’s awareness aboutStudent’s awareness about
the –the –
* Typical leaf structure* Typical leaf structure
* Essentiality of various* Essentiality of various
leaf parts in a plantleaf parts in a plant
* Familiarity about* Familiarity about
Phyllotaxy in plantsPhyllotaxy in plants

6. Lesson flow Technica
l
NonTeh
n-ical
Teache
r
Student
Why
To have an idea about
the importance
of leaf parts in a typical
leaf.
To catagorise the plants
on the basis of
phyllotaxy,
-- Verbal
com
muni
catio
n
Active Partly
active

7. What Tech.Tech. NonNon
Tech.Tech.
TeacherTeacher StudentStudent
Module on
Bhartiyavi
dya
Original
leaf
Specimens
Active Active
Definition of Leaf M
Parts of typicalLeaf M
Importance of these
parts
M
Definition of
Phyllotaxy
M
Types & subtypes of
Phyllotaxy
H

8. How Tech.Tech. NonNon
Tech.Tech.
TeacherTeacher StudentStudent
Activity:
Session of Q/A on leaf
structure & Phyllotaxy
Study the structure of Leaf
through original
specimens.
Look at the venation in leaf
specimens & study it.
Q/A onQ/A on
monitormonitor
Leaf
specimens
Active
through
explanation
Active

9. Question sessionQuestion session
Q. Give the definition of leaf.Q. Give the definition of leaf.
Q. What do you call the structure by which leaf is attached atQ. What do you call the structure by which leaf is attached at
plant?plant?
Q. Give the technical term for the mode of arrangement ofQ. Give the technical term for the mode of arrangement of
leaves on plant.leaves on plant.
Q. How many types of arrangement of leaves in plants areQ. How many types of arrangement of leaves in plants are
there/there/

10. What Else Tech.Tech. NonTechni-
cal
Teacher Student
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.
-- Collection ofCollection of
leaves samplesleaves samples
PassivePassive ActiveActive

11. 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.

12. Parts of the Leaf
1. Leaf Base2. Petiole3. Lamina
more

13. Leaf Base
The part of leaf attached to the stem or branch is
called- Leaf base. It protects a Bud in it’s axil.

14. 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.

15. 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.

16. 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

17. 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.

18. 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

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

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

21. 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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