What is not a function of the epidermis in plants?

The epidermis in plants serves several important functions, but photosynthesis is not one of them. The primary role of the epidermis is to act as a protective layer covering the plant's surfaces. It helps in preventing water loss through transpiration by forming a barrier, primarily through the presence of a waxy cuticle. This cuticle aids in retaining moisture, which is vital for the plant’s overall health.

Additionally, the epidermis protects against disease by serving as a first line of defense against pathogens and pests. It can also facilitate gas exchange to some extent, particularly through structures known as stomata, which are small openings that allow for the exchange of gases like oxygen and carbon dioxide.

In contrast, photosynthesis primarily occurs in the chloroplast-containing cells found in the mesophyll layer of leaves rather than in the epidermis. While the epidermis can contain some chloroplasts in certain plants (especially in some succulent species), these are not its functional focus or primary role, which is why photosynthesis is correctly identified as not being a function of the epidermis.