Epidermis
/ˌɛpɪˈdɝmɪs/
Definition
Epidermis is the outermost layer of cells covering young leaves, stems, roots, flowers, fruits, and seeds. It is a plant tissue, usually one cell thick, that forms the boundary between the plant and its environment. The epidermis helps limit water loss, protects inner tissues, and may contain specialized cells such as stomata for gas exchange, root hairs for absorption, and cells that produce the waxy cuticle.
Function in Plants
- Water-loss control: The epidermis helps limit drying by producing the cuticle, a waxy surface layer that slows water loss from leaves and young stems.
- Gas exchange through stomata: Specialized cells in the epidermis form stomata, tiny pores that regulate carbon dioxide entry, oxygen release, and water vapor loss during transpiration.
- First barrier against damage: This outer layer is the plant’s first contact with sun, wind, pests, and many pathogens, so its condition affects stress tolerance and disease entry.
- Site of surface outgrowths: Root hairs, leaf hairs, and some defensive structures develop from the epidermis, increasing water uptake, reducing heat stress, or discouraging herbivores depending on the organ.
Related Terms
Cuticle
Cuticle refers to the thin, waxy, water-resistant layer that covers the outer surface of most leaves, young stems…
Stoma
Stoma refers to a microscopic pore in the epidermis, the outer cell layer of leaves and young stems. Each stoma is…
Guard cell
Guard cell refers to one of the two specialized plant epidermal cells that surround a stoma, the tiny pore on a leaf or…
Trichome
Trichome refers to a small hair-like or scale-like outgrowth from a plant’s epidermis, the outer cell layer. It may be…
Pore
Pore refers to a small opening in a plant surface or cell wall. In plants, the term often describes stomatal pores on…
Gas exchange
Gas exchange refers to the movement of gases between a plant and the surrounding air, mainly carbon dioxide entering…
Leaf
Leaf refers to a plant organ, usually flat and green, that grows from the stem or a branch and is specialized for…
Root hair
Root hair refers to a tiny, tubular extension of a root epidermal cell, usually found near the growing tip on young…