1. Department of Botany, National Museum of Natural History Smithsonian Institution Washington DC 20013‐7012 USA
2. School of Ecology and Nature Conservation Beijing Forestry University Beijing 100083 China
3. State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany the Chinese Academy of Sciences Beijing 100093 China
4. Center for Documentation and Information Management, Institute of Botany the Chinese Academy of Sciences Beijing 100093 China