The adaxial (upper) epidermis and abaxial (lower) epidermis, both has a layer of conspicuous cuticle. The abaxial epidermis generally bears more stomata than the adaxial epidermis. The tatler may even lack stomata. The tissue between the upper and lower epidermis is called mesophyll. It contains palisade and spongy parenchyma. The vascular bundles represent the midrib and other veins. The xylem is adaxial and phloem is abaxial. The vascular bundles are surrounded by a layer of thin-walled bundle sheath cells.