What type of cells form the protective outer layer of a plant?

Epidermal cells are responsible for forming the protective outer layer of a plant, which is known as the epidermis. This layer serves multiple important functions, including protection against mechanical injury, pathogens, and excessive water loss. The epidermis is typically a single layer of tightly packed cells that provides a barrier to the external environment.

Epidermal cells often contain specialized structures, such as trichomes (hair-like structures) and guard cells that regulate gas exchange by controlling the opening and closing of stomata. This is crucial for maintaining the plant's overall health and facilitating processes like photosynthesis and respiration while minimizing water loss.

In contrast, parenchyma cells primarily serve roles in storage, photosynthesis, and tissue repair, cortex refers to the layer of tissue below the epidermis that typically provides support and storage, and conductive cells are involved in transporting water and nutrients throughout the plant. Thus, while all the other cell types play significant roles in the plant's biology, it is the epidermal cells that specifically form the outer protective layer.