Abstract: The Baiyandian Lake lies at 115°56′ E. and 38°55′ N. It is about 8 m above sea level, with an area about 312 square km. There are abundant aquatic plants here, including flowering plants of 30 families, 46 genera, 66 species and 3 varieties besides one introduced species. 32 species are erect ones covering about 48.5% of the total number of species in this lake, 20 are submerged ones, about 30.3%, 9 are leaf-floating ones, about 13.6% and 5 are floating ones, 7.6%. The soil at the bed of the lake is very fertile and the depth is appropriate, favouring various plants. The coverage is large, sometimes it may reach 100%, for example, in communities of Phragmites communis, Hydrilla verticillata, Hydrocharis dubis, Trapa bicornis, etc. Although the Baiyandian Lake is located in the temperate zone, the floristic elements are complex. There are tropic-subtropic elements and elements of high-frigid zone as well. When compared respectively with the floras of the Lakes Jingbo Lake, Honghu Lake and Lugu Lake, the flora of this lake is found more similar to that of subtropic Honghu Lake than to those of the other lakes, which shows that it hase a character transitional between the south and the north in China. Further studies of the floristic relationships are needed in order to exploit and use the resources of the aquatic plants in this lake.

Key words: Baiyangdian, flora, Living form