What is spongy mesophyl?

Spongy mesophyll is a layer of tissue found in the leaves of plants, situated beneath the palisade mesophyll and above the lower epidermis. It consists of loosely packed, irregularly shaped cells with air spaces that facilitate gas exchange, allowing carbon dioxide to diffuse into the leaf and oxygen to exit. This tissue plays a crucial role in photosynthesis and respiration by maximizing surface area for gas exchange while maintaining structural integrity. The spongy mesophyll also helps in water vapor retention within the leaf.