Origin and structure of the Kranz tissue in bracts of Cyperus giganteus Vahl (Cyperaceae)

Abstract

Cyperus giganteus shows Kranz anatomy of the clorocyperoid type or with two sheaths, one internal, adjacent to the vascular system and known as Kranz sheath, with thin-walled cells and a large number of organelles, mainly chloroplasts; and an external sheath, the mestome sheath or endodermis, the cells of which present thickened walls, are without chloroplasts and possess a suberin lamella, together with the casparian strip which are detected in early stages of differentiation. The development of the vascular bundles shows the Kranz sheath originating from the procambial as well as the mestome sheath. The chloroplasts of the Kranz cells are relatively larger, with convoluted thylakoids and a prominent peripheral reticulum, while the chloroplasts of the mesophyll cells are relatively smaller, with thylakoids forming grana and a sparse peripheral reticulum. These ultrastructural characteristics show similarities to those of other species of the genus Cyperus.