1. State Key Laboratory of Systematic and Evolutionary Botany Institute of Botany, Chinese Academy of Sciences 20 Nanxincun, Xiangshan Beijing 100093 China
2. College of Agriculture Shanxi Agricultural University Taigu 030801 China
3. Royal Botanic Garden Edinburgh 20a Inverleith Row Edinburgh EH35LR UK
4. Key Laboratory of Land Surface Pattern and Simulation Institute of Geographic Sciences and Nature Resources Research, Chinese Academy of Sciences Beijing 100101 China
5. University of Chinese Academy of Sciences Beijing 100049 China