Vitex trifolia var.simplicifolia (Viticis fructus)is not only valuable as a medicinal plant,but also ecologically important.It can function as a wind break,and it stabilizes sand and soil,and it conserves water. Predicting the impact of climate change on the spatial distribution of V.trifolia var.simplicifolia may provide a scientific basis and reference for the sustainable use of this important plant.Using a Maximum Entropy (MaxEnt)model,we simulated the geographical distribution of V.trifolia under the current climatic conditions in China based on species presence data at 126locations and data for 22environmental factors.Then,we used the model to predict the future distributions of V.trifoliain two periods(2050sand 2070s)under four different climate change scenarios.The results showed that the MaxEnt model was highly accurate(mean area under ROC curve,0.988).The main climatic factors influencing the geographic distribution of V.trifolia were altitude,mean diurnal air temperature range,precipitation in the coldest quarter,and precipitation in the driest month.The model simulations indicated that,under the four scenarios,V.trifolia will widen its distribution because of a rapid increase in suitable habitat areas and a slow increase in marginally suitable habitat areas.During the period of 2041-2060,the potential distribution area of suitable habitat would increase from the current ratio of 5.03%to 15.88%,17.00%,17.59%,and 23.11% under scenarios 1-4,respectively.The potential distribution area of marginally suitable habitat would increase from the current ratio of 8.86%to 11.09%,10.31%,11.53%,and 12.96%under scenarios 1-4,respectively.During the period of 2061-2080,the potential distribution area of suitable habitat would increase to 21.22%,22.21%,24.57%,and 30.66%under scenarios 1-4,respectively,and the potential distribution area of marginally suitable habitat would increase to 11.85%, 12.07%,13.99%,and 14.66%under scenarios 1-4,respectively.In terms of the spatial distribution of the potential habitat area of V.trifolia,both the distributional range and the center of distribution of suitable and marginally suitable habitat areas would shift from coastal areas to inland.The distribution of suitable habitat area in Hunan and Jiangxi provinces would increase rapidly.Especially in Sichuan Province,where there is only a small percentage of marginally suitable habitat area currently,the potential marginally suitable habitat area would increase,and the suitable habitat area would appear and increase rapidly under climate change.