rhizodermis

The rhizodermis is the outermost layer of cells in a plant's root. It is a primary tissue responsible for absorption and protection. Unlike the epidermis found on shoots, the rhizodermis is characterized by the frequent presence of root hairs, which are extensions of individual epidermal cells. These root hairs significantly increase the surface area available for water and mineral uptake from the soil. The cells of the rhizodermis are typically thin-walled and lack a cuticle, or have a very thin one, which facilitates the passage of water and dissolved nutrients. Its primary function is absorption, but it also provides a barrier against pathogens and mechanical injury. The rhizodermis develops from the protoderm of the root apical meristem. As the root grows and matures, the rhizodermis may be sloughed off and replaced by the exodermis in older regions.