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.
Subjects: Biological Sciences.