Water lily leaf. Light micrograph (LM) of a transverse section through the leaf of a water lily (Nympha sp.) plant. All aquatic plants (hydrophytes) have a similar structure. The upper epidermis of the leaf has a thin cuticle (top) underneath which is a multi-layered palisade mesophyll. In-between the palisade cells are elongated sclereids for support. Underneath this is the spongy mesophyll and large intercellular air spaces (lacunae, white). The vascular bundles (dense patches green) consist of xylem and phloem The base of the midrib, under the epidermis, consists of collenchyma cells. Modern taxonomists now consider water lilies to be basal angiosperms and are neither monocots or dicots. Magnification: x15 when printed at 10 centimetres wide.