What is the basic structure of a leaf?


●     Lamina

The flat and broad green coloured part of the leaf is called the leaf-blade or lamina. This part is mainly responsible for photosynthesis and is generally exposed to sunlight.

●     Petiole

It is a short stalk that connects the leaf to the stem.

Lamina and petiole

  • Stomata

The surface of the leaves contains tiny pores known as stomata. They help in gaseous exchange. The carbon dioxide enters in the leaf whereas the oxygen and water vapour leaves the leaf, through the stomata.

The number of stomata on the lower surface of the leaf is significantly greater than the number of stomata on the upper surface of the leaf.

Stomata

These pores are enclosed by cells called guard cells which regulate the opening and closing of the stomata.

●     Veins

On the leaf surface, there are thin lines called veins. They are small and thin Pipelines

that are responsible for the transport of food and water.

The veins arrange themselves in a specific pattern. This arrangement is called the venation. There are two types of venation: reticulate venation and parallel venation.

(i)  What is Reticulate venation?

When the veins make a network-like structure, it is called reticulate venation.

Reticulate venation

For example, Leaves of banyan and mango.

 

(ii)  What is Parallel venation?

When the veins run parallel to each other, it is known as parallel venation.

Parallel venation

For example, Leaves of banana and coconut.