The phenology of Chara vulgaris was studied.The specimens were collected four times from April 2004 to January 2005 (one sampling per season).The water temperature,pH,dissolved oxygen,specific conductance,maximum width and maximum depth were monitored at every sampling time.Eighteen main morphological characteristics of the Chara vulgaris were also observed and measured under the microscope.The results showed that all the environmental factors had different seasonal patts and some of the morphological characteristics had significant fluctuations,indicating differences in their seasonality.At the same time,some morphological characteristics were affected by the environmental parameters to some extent and the effect was primarily exhibited in its vegetative proportions; there was little effect on the sexual reproductive characteristics.Therefore,the relatively stable sexual reproductive characteristics can be used to identify the species.