Fig. 4
Eucommia ulmoides (E. ulmoides) sampling map. a The gray area in the figure represents the geographical range where the sampling sites of the 13 natural populations of E. ulmoides are located, b Enlarged figure of sampling sites of 8 natural populations of E. ulmoides in Hunan Province, c Adult tree of E. ulmoides natural population. The specific locations are as follows: Lianghe town, Gansu (LH); Wufeng town, Hubei (WF); Hejia town, Hubei (HJ); Donggongsi town, Guizhou (DGS); Zhongshan town, Guizhou (ZS); Jiangya forest farm, Hunan (JYLC); Jinyan town, Hunan (JY); Reshi town, Hunan (RS); Miaoertan town, Hunan (MET); Qianling town, Hunan (QL); Zhexi town, Hunan (ZX); Lean town, Hunan (LA); Dayongqiao Sub-district, Hunan (DYQ). (The maps are created by authors using ArcGIS software)