Leaf to chloroplast. Illustration of the anatomy of a flowering plant and the location of its chloroplasts, the site of photosynthesis. At top is a leaf. Below this are the leaf layers with chloroplasts in the palisade and spongy mesophyll layer (orange and green, cylindrical cells). Below this is a mesophyll cell with a large vacuole (orange), a nucleus (red) and chloroplasts (dark green). At bottom is a cutaway view of a chloroplast, showing the granum (stack) consisting of discs of thylakoid membranes (bottom). This is where chlorophyll is used to harness the energy of sunlight in photosynthesis. For this artwork with labels, see image C023/8811.