mesophyll The internal tissue of a leaf blade (lamina), consisting of parenchyma cells. There are two distinct forms. Palisade mesophyll lies just beneath the upper epidermis and consists of cells elongated at right angles to the leaf surface. They contain a large number of chloroplasts and their principal function is photosynthesis. Spongy mesophyll occupies most of the remainder of the lamina. It consists of spherical loosely arranged cells containing fewer chloroplasts than the palisade mesophyll. Between these cells are air spaces leading to the stomata.

mesophyll Internal parenchyma tissue of a plant leaf that lies between epidermal layers. Its main functions are photosynthesis and the storage of starch.

mesophyll Soft tissue located between the two layers of epidermis in a plant leaf. In most plants, mesophyll cells contain chlorophyll-producing structures called chloroplasts, which are essential to photosynthesis.

mesophyll In the classification of leaf sizes, a leaf that is 125–250 mm long, or 2025–18 225 mm² in area.