What replaces the epidermis in some plants?

The correct answer is periderm, which is a type of tissue that replaces the epidermis in some plants, particularly in woody plants as they mature. The epidermis is the outer layer of cells that protects young stems and leaves, but as the plant grows and undergoes secondary growth, the epidermis can become inadequate for protecting the plant.

Periderm forms as part of the bark and consists of three components: the cork cambium, cork cells, and phelloderm. The cork cells, which are produced by the cork cambium, provide a protective barrier against environmental factors such as moisture loss and pathogen invasion. This replacement is crucial for the longevity and overall health of the plant as it moves into its higher growth stages.

In contrast, xylem is a type of tissue responsible for transporting water and nutrients from roots to other parts of the plant, while phloem transports food produced during photosynthesis. Cambium refers to the layer of actively dividing cells that contributes to secondary growth by producing new layers of xylem and phloem, but it does not replace the epidermis itself. Thus, periderm plays the direct role in replacing the epidermal tissue in certain plant species as they mature.