You may have heard at some point that your skin is the largest organ in your body. Besides being large, your skin is very important because it protects everything underneath it from disease, temperature, and other physical damagethat may occur.Much like your skin, a plant has atissue system, a group of cells that works together for a very specific function, that forms the first line of defense against physical damage and disease. This tissue system is called thedermal tissue system, and it is the plant's outer protective coating.The dermal system itself consists of a layer of tightly packed cells called theepidermis. On most plant stems and leaves, the epidermis is covered with a waxy coating called thecuticle, which helps prevent water loss through the epidermis.