It is the outer protective layer of cells of a plant, which may be thickened by a cuticle. It consists of epidermis and epidermal outgrowth. Epidermis is the superficial layer covering the entire surface of the primary plant body. All the epidermal cells are living (parenchymatous) and contain vacuolated protoplasm. Stomata are the structures present in the epidermis of leaves. Epidermal outgrowths are of two kinds- trichomes and emergences.