Epidermis forms the entire outermost layer of the plant. It is made up of single cell layer. It protects all the internal parts of the plant.

On aerial parts, epidermis secretes waxy, water-resistant layer on their outer surface. This helps in protection against loss of water, mechanical injury and invasion of parasitic fungi. In leaves, epidermis consists of small pores called stomata.

These pores helps in the transpiration and exchange of gases, like oxygen and carbon dioxide for plants. In roots, epidermis have long hair-like parts that provide greater surface for water absorption.

In desert plants, epidermis has a thick waxy coating of cut in which acts as a water proofing agent.