The epidermis serves several functions like :

epidermis is the  outermost layer of plant parts . protoderm-derived layer of cells covering the stem, root, leaf, flower, fruit, and seed parts of a plant. The epidermis and its waxy cuticle provide a protective barrier against mechanical injury, water loss, and infection. Root hairs araised from epidermal cells are used to absorb water and minerals , lenticels are formed  on epidermis during secondary growth for gaseous exchange .