Light micrograph of the leaf of the bog moss, Sphagnum sp. . A continuous network of true cells surrounds numerous wide, partitioned chambers. The true cells are highly elongated and contain chloroplasts. 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: x130 when printed at 10 centimetres wide at its longest edge.