Epidermal tissue system: It is the outermost protective tissue of the plant organs. It is derived from Protoderm and consists of epidermis, stomata and epidermal outgrowths. 

(i) Epidermis: (a) Epidermis is usually single layered, but in the leaves of some tropical plants it is more than one layer in thickness

(b) There is a layer of cutin, on the outer side of the epidermis of aerial parts of the plants called cuticle. 

(c) Epidermis along with cuticle protect the inner cells against loss of water, mechanical injury, attack of pathogens and leaching effect of rain. 

(d) The epidermis of grasses and cereals has a deposition of silica. 

(ii) Stomata are structures present in the epidermis of leaves which regulates the process of transpiration and gaseous exchange. 

(iii) Epidermal outgrowths: (a) The epidermis of most plants often bear outgrowths called epidermal outgrowths. They are of two type – Trichomes and hairs. 

(a) On the stem, the epidermal hairs are called trichomes. They are usually multicellular, branched or unbranched and soft or stiff. They may be secondary also. The trichomes help in preventing water loss due to transpiration. 

(b) The root epidermis bears unicellular outgrowths called root hairs. It is therefore, also called piliferous layer or epiblema. It is mainly concerned with the absorption of water and minerals from the soil.