A Study of Stomatal Structure in Pandanaceae

Abstract

Many species of Pandanaceae have unspecialized stomata. In species of Pandanus there is a range of stomatal structure involving increasing elaboration of papillae arising from subsidiary and neighbouring cells so that guard cells, which are otherwise constant in structure throughout the family, are increasingly provided with a canopy of papillae which, together with sinking of the stomatal apparatus, produces an outer stomatal chamber. In the most specialized stomata this chamber is itself virtually occluded by lobed papillae. Freycinetia may show significant differences from Pandanus. This linear trend of specialization can often be partly or wholly demonstrated on a single individual because stomata are always unspecialized on the first scalelike leaves of each renewal shoot, thereafter being increasingly specialized on subsequent leaves until the maximum potential elaboration characteristic of the species is realised on foliage leaves. This is briefly discussed in relation to taxonomy, physiology, and ecology.