cross section: Nerium leaf common name: Oleander magnification: 100x

Both the adaxial and abaxial epidermis in Nerium are multiseriate, being composed of up to three layers of compactly arranged cells with heavily cutinized outer walls. A heavy waxy cuticle is especially well developed on the light exposed adaxial surface. Stomata are limited to the abaxial surface where they are sunken within deep, trichome lined pits that serve to reduce transpirational water loss.

Three or more layers of tightly packed photosynthetic palisade mesophyll can be seen just beneath adaxial epidermis. In some specimens a single layer of shorter palisade mesophyll cells may be present towards the abaxial surface. The center of the leaf is occupied by a spongy mesophyll with abundant intracellular spaces and occasional calcium oxalate crystals.

Vascular bundles of the blade and midrib and smaller are closed and collateral with xylem towards the adaxial surface and phloem towards the abaxial surface. All vascular bundles are surrounded by parenchymatous bundle sheaths. The mid rib vascular bundle is large with a nearly continuous ring of supportive sclerenchyma, overlaid by storage parenchyma and further reinforced by masses of subepidermal collenchyma. All these tissues are particularly well developed towards the abaxial surface.