Structure of Leaves

One of the most important parts of a plant is the leaf. Leaves are considered as the kitchen of a plant because within it plants synthesize their food. Leaves act as the breathing organ too. Leaves also help the plants to get rid of excess water from it. This plant organ shows many varieties in its structure and function.

Definition: The lateral green appendage of the shoot system, which helps in production of food of a plant by photosynthesis, is known as leaf.

Mango leaf is a flat, green lateral appendage of a stem or its branch. It arises from a node. The flat expanded portion of a leaf is called leaf lamina. It is held by a small stick-like part, called leaf stalk or petiole. This type of leaf is known as petiolate leaf.

Some leaves do not have any petiole, they grow directly from a node. These leaves are called sessile leaf. The examples of these leaves are grass, bamboo plant etc. The base of the stalk is slightly swollen. This portion is called leaf base or pulvinus. Along the mid line of the lamina there is a rib-like structure, it is called midrib. It extends from the petiole to the tip of the lamina. Midrib is thicker at the base and gradually becomes finer towards the apex of a leaf.

The midrib gives off several branches and sub-branches, which are spread all over the lamina. These are known as veins. The arrangement of veins on a leaf lamina is called venation. In mango leaf the veins are arranged as a complex network. So this is known as reticulate venation.

Some other leaves have veins arranged parallel and they are called parallel venation, which is found in banana leaf.

In some leaves, like china-rose, a small thin leafy structure is found, normally in pairs, at the base of the petiole. This is called stipule. The leaves with stipules at their base are called stipulate leaf. Leaves of mango, banyan and jackfruit plants do not have stipule, these are called nonstipulate leaf.

Mango leaf has a single lamina on its petiole, so it is called a simple leaf. We will find several

plants around our place with simple leaves. But some plants are there in which the lamina of the leaf is divided into many small leaflets. These leaves are called compound leaves. They are the leaves of tamarind and gold-mohar.




Fifth Grade

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