Leaves account for most of the surface area of a plant. Leaves are a major interface between plants and their environment. Leaves perform the majority of photosynthesis in the plant. Leaves can be heavily modified and adapted for: An entirely different function (e. g. storage organ) Simple leaves- single lamina, compound leaves- many leaflets. Phyllotaxis- arrangement of leaves on a stem (not on exam) Palisade mesophyll- rich in chloroplasts, most of light capturing, elongates, most of photosynthesis occurs here, packed closely together to maximise light absorption, found in the upper part of the leaf under the upper epidermis. Spongy mesophyll- round and regular, not as closely packed as the palisade mesophyll, creates air spaces within the leaves to allow gases to move in and out, not as many chloroplasts here but photosynthesis still occurs. Vascular bundle- contain transporting tissue, xylem, phloem, moving water and photosynthetic products, structural features in young stems- form a network of veins.