Which is the ventral surface of the leaf?

The epidermis is the outermost layer of a leaf, present on both sides. It is called the upper epidermis on the top and the lower epidermis on the bottom. Botanists also refer to the upper side as the adaxial surface and the lower side as the abaxial surface. The epidermis plays an important role in regulating gas exchange.

The stomata, mostly found on the lower surface, control transpiration. The leaf surface area helps determine the number of stomata, which can increase or decrease the rate of water loss. The upper surface of the leaf, also called the ventral surface, usually contains more chlorophyll, giving it a darker green color since it faces the sun.

A waxy layer called the cuticle covers the leaf surface of most plants. The cuticle reduces water loss by slowing evaporation. Some leaves also have tiny hairs called trichomes, which serve multiple purposes:

• Protect against herbivores by restricting insect movement or storing toxic or unpalatable compounds.
• Reduce transpiration by blocking airflow over the leaf surface.