Tea leaf. Light micrograph of a section through the midrib of a tea (Camellia sinensis) leaf. The upper and lower epidermis on the surfaces of the leaf are blue. Under the upper epidermis are palisade cells (brown), which contain chloroplasts, the site of photosynthesis. Within the midrib is a vascular bundle, composed of xylem (red) and phloem (blue) cells, which transport water and carbohydrates around the plant respectively.