Explanation

The leaves of dicot plants are anatomically differentiated into epidermis, mesophyll tissue and vascular bundles. Mesophyll tissue is divided into upper palisade tissue, consisting of closely arranged cells with numerous chloroplasts and lower spongy tissue, which consists of loosely arranged cells separated by large air spaces. The cells of spongy tissue have fewer chloroplasts, hence most of the photosynthesis occur in palisade tissue.