Parts of a Leaf and Their Function | Science Lesson

This video lesson is designed for 3-6-year-old children. It demonstrates the basic structure of a leaf and its parts.

This science lesson provides a practical life experience by introducing the child to the different shapes and colors of leaves. It guides the child about the structure of a leaf and its characteristics by labeling the different parts of the leaf, like the apex, veins, stem, etc.

What is a Leaf?

A leaf is a plant organ that is flat, thin, and usually green in color. It is also called the kitchen of the plant as it is responsible for making food for itself as well as other parts of the plant.

Leaves are green in color because the pigment is called chlorophyll which helps plants to prepare food through photosynthesis.

Leaves vary in different shapes, sizes, and colors based on the plant type and are generally Dorso-ventrally flattened and thin.

What are the Parts of the Leaf?

A leaf has two main parts: The leaf blade and the Stalk or the petiole.

A. Stem / Petiole

A petiole is a stalk-like structure that connects a leaf to the plant’s stem. It is made of vascular tissues.

Functions of Stem

It provides support to the leaf and keeps it erect.
It transports water and nutrients absorbed by the roots to the leaves.
It transports food to the rest of the plant.

B. Leaf-blade or Lamina

It is the thin, flat part of the leaf that is typically green in color. It is characterized by green color, thinness, and smoothness. The leaf is divided into three parts: i) leaf apex – the tip of the leaf blade; ii) leaf margin – the edge of the leaf; and iii) leaf veins – tiny capillaries.

Functions of Leaf Blade

It helps plants prepare their food using raw materials like water, carbon dioxide, and minerals through photosynthesis.
It helps to perform transpiration.

Note: Some plants also contain a third part of the leaf called stipules. These are small flap-like structures that grow at the base of the petioles. Also, some leaves are directly attached to the stem without the petioles and are called sessile leaves. Saffron and Achyranthes plants have sessile leaves.

Let us now understand the structure of the leaf using two different-looking leaves, as shown in the video.

What is the Structure of a Leaf Blade?

As discussed above, the leaf blade is divided into different parts

1. Stomata

Stomata are the minute pores present on the surface of the leaf.

Functions of Stomata

It helps to release the oxygen and absorbs carbon dioxide from the atmosphere
It helps in the movement of water vapors.

2. Veins

Leaf veins are divided into two parts: the main/ central vein and the side veins. It helps in transporting water and nutrients throughout the leaf.

a. The main vein or the midrib: The main vein is like the backbone of the smaller vein to transport important nutrients from leaves to different parts of the plant.

Functions of Main Vein:

It helps the leaf to keep in an upright position and keeps the leaf strong during the wind flow
It supports the leaf to stand and exposes it to proper sunlight.

b. Side Veins: Side veins are the lateral extensions that develop from the midrib of the leaf and extend towards the leaf margin. It is like a network of veins that reaches every stoma of the leaves, collects the food, and transports it to the main vein of the leaf.

3. Apex

Apex is a protruding part of a leaf where water droplets accumulate, and droplet separation occurs during drainage.

Function of Apex

It helps in draining excess water without damaging the structure of the leaf.

4. Leaf Margin

The leaf margin allows the leaf to have a hard surface and reduces water loss.

Invite the child for a walk in your garden and ask them to pick a leaf and name the different parts, as shown in the video. Encourage them to connect with nature as they explore their surroundings.

FAQs

What are the external parts of a leaf?

The external parts of the leaf are the petiole, leaf base, lamina, leaf apex, and leaf margins.

What are the internal parts of a leaf?

The internal parts of the leaf are stomata, guard cells, epidermal cells, mesophyll cells, and vascular bundles (xylem, phloem, veins)

Which part of the leaf helps in exchanging gases?

Stomata are tiny pores present on the surface of the leaves that help in exchanging gases, i.e. absorption of carbon dioxide and release of oxygen.

Parts of the Leaf