Most photosynthetic cells in plants are located in the leaves, specifically in the photosynthetic tissues of the mesophyll. Within the leaf, the palisade mesophyll cells near the upper surface contain many chloroplasts and are the primary site of photosynthesis, while the spongy mesophyll beneath them also contributes by housing chloroplasts and facilitating gas exchange. In addition, some photosynthesis occurs in chloroplasts of other green tissues (e.g., younger stems or fruits) that contain chloroplasts, but leaves dominate overall photosynthetic activity.
