Abstract：The anatomy and apoplastic barrier of Oenanthe javanica（Bl.）DC. roots and stems were studied by optical and epifluorescence microscopes．The results showed that the adventitious roots were primary structure of O. javanica（Bl.）DC.，and had diarch and triarch vascular cylinder，endodermis，cortex，hypodermis and epidermis．Its stems were also of primary structure，and had pith cavity，cortex，and cortex with aerenchyma and scattered vascular bundles，collenchyma and epidermis．The air spaces in vivo included aerenchyma in adventitious roots and pith cavity and cortical aerenchyma in stems．The apoplastic barriers in adventitious roots included the inner layers of endodermis with Casparian bands and suberin，and the outer layers were consisted of suberized epidermis，lignified hypodermis and suberized walls around aerenchyma in different development stages，and cuticle and lignified collenchyma in stems．The in vivo air spaces and apoplastic barriers are important sturactural assurances for O. javanica（Bl.）DC. to adapt to wetland environment and improve wetland aeration．