What are the inner cells of leaves called? 

The mesophyll is situated between the top and lower epidermis and helps in gas exchange and photosynthesis through chloroplasts. The xylem carries water and minerals to the leaves, whereas the phloem carries photosynthetic products to other sections of the plant.

Mesophyll cells are the key places of photosynthesis. The inner tissue (parenchyma) of a leaf is called mesophyll. It is differentiated into palisade and spongy mesophyll cells.

Guard cells are specialized cells that surround stomata, which are small openings in the epidermis of leaves, stems, and organs. 

Stomata are the pores in the epidermis of leaves, stems, and organs that allow for the exchange of gases, such as carbon dioxide and oxygen, as well as water vapour. 

The epidermis is the outermost layer of cells that covers the surface of leaves, stems, and organs of plants.