Light micrograph (fluorescence microscopy) of the leaf of the bog moss, Sphagnum sp. . A continuous network of true cells (red) surrounds numerous wide, partitioned chambers. The true cells are highly elongated and contain chloroplasts (which fluoresce in red under ultraviolet light). The partitioned chambers retain water and give the plant its sponge-like properties. Because of its water holding capacity, sphagnum is often used as a packing material for the transportation of other cultivated plants. Magnification: x70 when printed at 10 centimetres wide at its longest edge.