The Ultrastructure of Kranz Cells in the Family Cyperaceae

The anatomy of the leaves and ultrastructure of the photosynthetic cells of 18 Cyperus and five Fimbristylis species with Kranz anatomy have been examined and described. The Kranz cells are all centripetal to the mestome sheath, and their ultrastructure conforms to the pattern previously reported in NADP-ME-type species, which are characterized by high NADP malic enzyme activity and form one of three subgroups of C4 pathway species based on differing C4 acid decarboxylating systems. In some Cyperus species the peripheral reticulum is arranged in radial bands of regular vesicles in denser staining stroma, alternating with radial bands showing less regular organization and staining less deeply; Fimbristylis never shows this arrangement.