Palisade cells are plant cells located on the leaves, right below the epidermis and cuticle. They are vertically elongated, a different shape from the spongy mesophyll cells beneath them. The chloroplasts in these cells absorb a major portion of the light energy used by the leaf. Palisade cells occur in dicotyledonous plants, and also in the net-veined monocots, the Araceae and Dioscoreaceae.
Palisade cells contain the largest number of chloroplasts per cell, which makes them the primary site of photosynthesis in the leaves of those plants that contain them, converting the energy in light to the chemical energy of carbohydrates.
Beneath the palisade mesophyll are the spongy mesophyll cells, which also perform photosynthesis, they are irregularly shaped cells that have many intercellular spaces that allow the passage of gases.
Holt Science & Technology "Microorganisms, Fungi, and Plants", Holt, Rinehart and Winston