Camphor leaf surface. Coloured scanning electron micrograph (SEM) of the surface of a leaf of the camphor tree (Cinnamomum camphora). Mid-green epidermal cells provide support and secrete a waxy cuticle to protect the leaf and limit water loss. Between the epidermal cells are paler green cells containing stomata (leaf pores), through which gaseous exchange occurs. Stomata are opened and closed by changes in pressure in the guard cells on either side of the pore. Crystals of a substance called camphor can be extracted from the leaves and wood of C. camphora. It is used in herbal medicine to treat many complaints. Magnification: x150 when printed 10cm wide.