Oleanders grow in Mediterranean regions with hot and dry summers. As a protection against desiccation the leaf has evolved xeromorph adaptations: the stomata are located in pockets formed by the lower (abaxial) leaf epidermis. In addition the underepidermis bears numerous hairs that also limit evaporation. With this double protection the stomata can slightly protrude inside the humid pocket without risk. Notice the typical wall thickenings of the guard cells.