Upper Epidermis - single layer of cells including no or few chloroplasts. The upper epidermis is covered in a waxy layer called the cuticle. The cuticle reduces water loss from the leaves.

Palisade Layer - one or more layers of cells that sit perpendicular to the plane of the leaf. These cells contain several dozen chloroplasts that carry on most of the photosynthesis in the leaf.

Spongy Layer - sits below the palisade layer and consists of loose and irregular shaped cells. This layer contains few chloroplasts but is a major component for storage of sugars and amino acids. Air spaces between the cells give off oxygen and water vapor. These spaces eventually lead to the outside through pores of the leaves called stomata.

Lower Epidermis - most of the stomata are located in this layer. Guard cells surround the stoma that regulate opening and closing of the stomata. This controls exchange of gases between the leaf and surrounding atmosphere.