Slide 5: shows a face view of the undersurface of the epidermis of a leaf. Most epidermal cells are relatively flat and usually the epidermis is only one layer thick. Here the cells are irregularly shaped and lock together like pieces of a puzzle, leaving no intercellular spaces. Such tight connections aid in protection against loss of water, mechanical injury, and invasion by parasitic fungi. Notice the three stomatal openings and their associated guard cells.