Flora of China Aponogetonaceae Author Guo Youhao Cymodoceaceae Author Guo Youhao Hydrocharitaceae Author Guo Youhao Juncaginaceae Author Guo Youhao Najadaceae Author co-authoring Posidoniaceae Author Guo Youhao Potamogetonaceae Author Guo Youhao Ruppiaceae Author Guo Youhao Scheuchzeriaceae Author Guo Youhao Triuridaceae Author Guo Youhao Zannichelliaceae Author Guo Youhao Zosteraceae Author Guo Youhao