A STUDY ON COMMUNITIES OF AQUATIC VASCULAR PLANTS IN FOUR COUNTIES IN QINGHAI-XIZANG

Maduo and Dart counties of Qinghai Province, Jiuzhi county of Ganshu Province and Aha county of Sichuan Province are located in upper of river system of Huang He.Above counties an important part of distribution area of aquatic vascular plants in Qinghai-Xizang Plateau.9 aquatic plant communities distribut in the area, they are Co., Co.Potamogeton amblyophyllus, Co.Potamogeton pamiricum,Co.Halerpestes cymbaria, Co.Beckmannia syziachne,Co.Batranchium bungei var.fovidum, Co.Alopecurus aequalis, Co.Sparganium fatlax, Co.Polygonum sibiricum.Above communities contain 14 species of aquatic vascular plants.North Temperate species in the communities are main distribution type in these communities.