Christmas rose leaf. Coloured scanning electron micrograph (SEM) of a section through the leaf of the Christmas rose (Helleborus niger). The upper surface of the leaf is at top. Below this are numerous vertical cells containing chloroplasts (small spheres). Chloroplasts are organelles which are the site of photosynthesis within the leaf. Photosynthesis is the process by which plants use sunlight to turn carbon dioxide into sugars. At lower right (blue) is a vascular bundle, part of the network of veins which transports water and nutrients to and from the leaf. Magnification: x140 at 6x7cm size. x210 at 4x5"~SQUARE"