Tissue between the upper and lower epidermis of a leaf blade (
lamina), consisting of parenchyma-like cells containing numerous
chloroplasts.
In many plants, mesophyll is divided into two distinct layers.
The
palisade mesophyll is usually just below the upper epidermis and is composed of regular layers of elongated cells. Lying below them is the
spongy mesophyll, composed of loosely arranged cells of irregular shape. This layer contains fewer chloroplasts and has many intercellular spaces for the diffusion of gases (required for
respiration and
photosynthesis), linked to the outside by means of
stomata.
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