The epidermis of the leaf is thick walled and has a thin layer of cuticle; it helps in preventing the excessive loss of water. The epidermal layers also possess numerous minute openings known as stomata. The stomata takes part in the important physiological functions like photosynthesis, respiration and transpiration etc. The epidermis of the stem, root and leaves have epidermal hairs; the uptake of water takes place through these epidermal root hairs. The epidermal hairs of stem and leaves are commonly known as the trichomes; it sometimes produces certain compounds. So all these functions together make the epidermal cells important to leaves.