Witch-hazel leaf surface. Coloured scanning electron micrograph (SEM) of the upper surface of a witch-hazel (Hamamelis virginiana) leaf. Veins (vascular bundles) branch across the surface (grey). These contain xylem and phloem, which conduct water and nutrients throughout the leaf. The star- shaped structure is a hair cell or trichome. The blade of the leaf is formed of a layer of epidermal cells (green), among which are stomata (leaf pores, white). These are the sites of gaseous exchange. Witch-hazel is used in herbal medicine to treat sprains, burns and skin inflammation. Magnification: x80 when printed 10 centimetres wide.