KRANZKETTE, A UNIQUE C-4 ANATOMY OCCURRING IN CYPERUS-JAPONICUS LEAVES

Cyperus japonicus Mak., which has a widespread distribution in subtrop ical Asia and extends northwards into Europe, was found to be a C-4 sp ecies based upon its Kranz leaf anatomy, low CO2 compensation concentr ation and isotopic composition of leaf carbon. A curious variant of th e anatomical arrangement of photosynthetic cells is developed in this wetland species. Connected by veins, two groups of Kranz units, one un derneath the abaxial epidermis and the other in the middle of the blad e, form elliptical mesophyll channels. This arrangement of Kranz units has been defined as Kranzkette (literally ''the chain of garland''). Like Cyperus longus, another C-4 species in the genus, the structure a nd arrangement of chloroplasts in the bundle sheath cells show it to b e a NADP-ME type. Starch grains, however, are formed in both mesophyll and bundle sheath cells. This modified C-4 Kranz anatomy with large i ntercellular air spaces within the chlorenchyma suggests that the arra ngement of assimilatory cells may be related to gas transport through the large air-spaces.