The part of a plant that performs the majority of photosynthesis is the leaves. Their broad, usually thin surfaces capture sunlight and provide an efficient area for exchanging carbon dioxide and oxygen.
Most photosynthesis takes place in mesophyll cells inside the leaf. These cells contain chloroplasts, the organelles where light-dependent reactions and carbon fixation occur. Chlorophyll in the chloroplasts absorbs mainly blue and red wavelengths, while green light is absorbed less strongly and contributes to the leaf’s green appearance.
Leaves are also built for gas exchange. Tiny pores called stomata allow carbon dioxide to enter and oxygen and water vapor to leave. Veins deliver water and minerals through the xylem and carry sugars away through the phloem. This close connection between light capture, gas exchange, and transport makes leaves the plant’s main photosynthetic organs.
Other green parts can photosynthesize too. Young stems, green fruit, and some sepals may contribute, especially when leaves are absent or immature. Roots generally lack light and chlorophyll, while flowers are primarily reproductive structures rather than the plant’s main photosynthetic tissue.