These two layers (palisade and spongy parenchyma) make up the mesophyll which is the ground tissue of the leaf. The mesophyll is enclosed between epidermal cells which secrete a waxy substance called cutin. The cutin forms a coating, the cuticle, over the outer surface of the epidermis. The epidermal cells and the cuticle only permit light to penetrate to the photosynthetic cell s. Water and dissolved minerals are transported into and out of leaves by the way of vascular bundles which are known in leaves as veins (xylem and phloem) . Veins are conspicuously different in monocots and dicots. In monocots the major veins are usually parallel and in dicots the veins are usually netted. Gases (o2 and co2) move into and out of leaves by diffusion through stomata. Stomata consist of a small opening or pore, guard cells, which open and close the pore.…
