Abstract:

This research studied the vegetative organs of Cyperus rotundus distributed in the drawdown zone of the Three Gorges Reservoir and Jianghan Floodplain along the Yangtze River. In this study samples were sectioned under an anatomical microscope and we used histochemical， optical and fluorescence microscopy methods to observe， photograph and record the anatomical structure and histochemical characteristics of leaves， erect stems， rhizomes， tubers and adventitious roots of C. rotundus adapted to amphibious environment. It was found that： 1） C.s rotundus has typical characteristics for adaption to an amphibious environment， including tissue air cavities and an apoplastic barrier in roots. Air cavities were observed in the lysed aerenchyma in the adventitious roots， rhizomes and leaves and schizogenous aerenchyma in erect stems. The apoplastic barrier included endodermis， exodermis， suberized stele and vascular bundle sheaths. 2） The adventitious roots of C. rotundus have a suberized stele， while stems have suberized vascular bundles， and the Kranz anatomy of leaves and erect stems consists of three layers： inner sheaths， mestome sheaths and parenchymatous sheaths. 3） The apoplastic barrier of C. rotundus may help to retain oxygen and control the exchange of water and ions between the environment and plant tissues under submersion. The air cavities are conducive to the preservation and transport of oxygen for aerobic metabolism. The adaptation of C. rotundus to submerged terrestrial environments indicates that it is likely to be an important species for ecological restoration of the Yangtze River.

Key words: Cyperus rotundus, anatomical structure, amphibious, histochemical features, apoplastic barrier