Question

Describe the internal structure of a dorsiventral leaf with the help of labelled diagrams.

Answer 1

Part 1 : Definition of dorsiventral leaf
Dorsiventral leaves are majorly found in dicot plants. In such leaves the structure varies from upper to lower surface.

Part 2: Internal structures of dorsiventral leaf
The internal structures of dorsiventral leaf are, epidermis, mesophyll and vascular system.

Part 3 : Epidermis
The outermost layer of the leaf is called epidermis. The upper (adaxial) and lower (abaxial). The upper epidermis consists of very less or no stomata, whereas the number of stomata is more in the lower epidermis. This arrangement of stomata in the dorsiventral leaves reduces the loss of water due to transpiration.

Part 4: Mesophyll
The parenchymatous cells present between the upper and lower epidermis in a dorsiventral leaf are called mesophyll cells. These cells play a major role in the process of photosynthesis. There are two types of mesophyll cells - palisade parenchyma and spongy parenchyma. Palisade parenchyma :Elongated mesophyll cells, which are located near the upper epidermis. Spongy parenchyma : Irregular shaped cells that are loosely arranged towards the lower epidermis.

Part 5 : Vascular system
The vascular bundles are surrounded by a layer of thick-walled bundle sheath cells (these cells are photosynthetic and help in forming a protective layer on the leaf surface). They are conjoint (xylem and phloem are arranged along the same radius) and closed (vascular bundle which lacks cambium).

Part 6: Diagram