Epidermis
The epidermis is the outermost layer of cells in plants, forming a protective barrier between the internal tissues and the external environment. In leaves, it consists of an upper and lower epidermis, both of which help regulate water loss, gas exchange, and protect against physical damage or pathogens. The epidermis is often covered with a waxy layer called the Cuticle, which minimizes water loss through evaporation.
Specialized structures in the epidermis, such as Stomata and Guard Cells, play a crucial role in controlling the exchange of gases like oxygen, carbon dioxide, and water vapor. In addition to leaves, the epidermis covers stems and roots, adapting to different functions such as water absorption in roots or protection from herbivory in stems.