Spinach leaf. Coloured scanning electron micrograph (SEM) of a fractured leaf of the spinach plant, Spinacia oleracea. At top and bottom frame are a single layer of cells (light green) which form the epidermis of the leaf. The leaf interior contains palisade mesophyll (dark green) & spongy mesophyll (light green). The tightly packed palisade cells contain chloroplasts, sites of photosynthesis. The spongy mesophyll cells have with fewer chloroplasts; they are more involved with gas exchange. Magnification: x219 at 6x7cm size.