Monocotyledon leaf. Illustration showing the anatomy and cell structure of a monocotyledon leaf. The lower surface of the leaf is seen at top. Stomata (brown, pores) are present on the lower epidermis through which gaseous exchange occurs. Under the one-cell thick epidermis, spongy mesophyll cells are found loosely packed (grey). Leaf veins occur in parallel in monocotyledons. Here, two veins (vascular bundles) are seen among mesophyll cells. Schlerenchyma sheath cells (yellow) strengthen the vein; within the sheath are xylem (pink) and phloem (white) cells which transport water and nutrients.