Which term describes the protective outer layer of a plant?

The term that describes the protective outer layer of a plant is the epidermis. The epidermis serves as a crucial barrier that protects plant tissues from physical damage and pathogens. It plays a key role in regulating water loss by controlling the exchange of gases and moisture through structures called stomata, which are present in this layer. The epidermis is usually made up of a single layer of cells and may also be covered by a cuticle, a waxy coating that helps reduce water loss, further enhancing its protective function.

Other terms listed do not refer specifically to the outer protective layer. The cortex, for example, is found beneath the epidermis and typically functions in storage and transport of nutrients. Phloem is part of the vascular system responsible for the transport of sugars and other organic compounds. The endodermis is a specialized layer in the roots that regulates the movement of water and nutrients into the vascular system, but it is situated deeper in the plant structure. Thus, the epidermis is the most accurate term for the outer protective layer.