leaf

Lesson PlanLesson PlanBIOLOGYBIOLOGY

Std. -XStd. -XII

Concept

Study of the Leaf structure & Phyllotaxy in plants.

PurposePurpose Awareness about the Awareness about the

structure of a typical structure of a typical leaf & the types of leaf & the types of Phyllotaxy in plants for Phyllotaxy in plants for their mode of their mode of arrangementarrangement

CategoryCategory & Time& Time Medium Medium 40-45 minutes40-45 minutes

Learning OutcomesLearning Outcomes

Student’s awareness about Student’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

Lesson flow Technical

NonTehn-ical

Teacher

Student

WhyTo have an idea about

the importance of leaf parts in a typical

leaf.To catagorise the plants

on the basis of phyllotaxy,

-- Verbal communication

Active Partly active

What Tech.Tech. Non Non Tech.Tech.

TeacherTeacher StudentStudent

Module on Bhartiyavidya

Original leaf Specimens

Active ActiveDefinition of Leaf M

Parts of typicalLeaf M

Importance of these parts

M

Definition of Phyllotaxy

M

Types & subtypes ofPhyllotaxy

H

How Tech.Tech. Non Non Tech.Tech.

TeacherTeacher StudentStudent

Activity: Session of Q/A on leaf

structure & PhyllotaxyStudy the structure of Leaf

through original specimens.

Look at the venation in leaf specimens & study it.

Q/A on Q/A on monitormonitor

Leaf specimens

Active through

explanation

Active

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 at Q. What do you call the structure by which leaf is attached at

plant?plant?Q. Give the technical term for the mode of arrangement of Q. 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 are Q. How many types of arrangement of leaves in plants are

there/there/

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 downthe missing parts.

-- Collection of Collection of leaves samplesleaves samples

PassivePassive ActiveActive

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.

LaminaIt 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 decussateOpposite 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.html#Structure

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