Dermal tissue functions to protect the plant from injury and water loss. Dermal tissue covers the outside of the plant, except in woody shrubs and trees, which have bark. The most common cell type in dermal tissue is the epidermal cell. Generally, a thin, waxy layer called a cuticle covers the epidermal cells and protects them. Other cells in the dermal tissue are guard cells that surround the stomata, which are openings in the leaves. Gases and water enter and leave the dermal tissue through the stomata.