How many cells thick is the upper epidermis?

The upper epidermis of a leaf cell is composed of a single layer of cells. The cells do not contain chloroplasts and are virtually transparent.

A typical dicot leaf has four layers of tissues: the upper epidermis, the palisade layer, the spongy layer and the lower epidermis. The upper epidermis is virtually transparent to allow light to pass through to the deeper layers of the leaf. The deeper layers contain chloroplasts which help the plant undergo photosynthesis for energy. The upper epidermis is also covered with a waxy cuticle that helps the four layers of tissues to retain water and stay hydrated.