Flase colour scanning electron micrograph of a cross section through a white dead nettle stem, Lamium album, showing the hexagonal pith cells. The pith consists of large empty cells, often as broad as they are long. The cell walls are typically thin with air spaces between them, visible where three cells come together imperfectly. These cells degenerate as the stem grows to give rise to a hollow central cavity. Magnification: X540 at 10x8 inch, X77 at 35mm size Colorvir, yellow/red.