Epidermis (botany)

The epidermis (from the Greek ἐπιδερμίς, meaning "over-skin") is a single layer of cells that covers the leaves, flowers, roots and stems of plants.

Some plants like Ficus elastica and Peperomia, which have a periclinal cellular division within the protoderm of the leaves, have an epidermis with multiple cell layers.

Particularly, wavy pavement cells are suggested to play a pivotal role in preventing or guiding cracks in the epidermis.

The cuticle reduces water loss to the atmosphere, it is sometimes covered with wax in smooth sheets, granules, plates, tubes, or filaments.

Surface wax acts as a moisture barrier and protects the plant from intense sunlight and wind.

In plants with secondary growth, the epidermis of roots and stems is usually replaced by a periderm through the action of a cork cambium.

Expression of the gene MIXTA, or its analogue in other species, later in the process of cellular differentiation will cause the formation of conical cells over trichomes.

Stomatal patterning is a much more controlled process, as the stoma affects the plant's water retention and respiration capabilities.

Stomata are pores in the plant epidermis that are surrounded by two guard cells, which control the opening and closing of the aperture.

It is thought that plant hormones, such as ethylene and cytokines, control the stomatal developmental response to the environmental conditions.

Accumulation of these hormones appears to cause increased stomatal density such as when the plants are kept in closed environments.