1. College of Life Sciences Shanxi Normal University Linfen 041000 China
2. State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany Chinese Academy of Sciences Beijing 100093 China
3. University of Chinese Academy of Sciences Beijing 100049 China
4. School of Life Sciences, Nanjing University Nanjing 210023 China
5. Department of Botany, National Museum of Natural History Smithsonian Institution Washington DC 20013‐7012 USA