1. State Key Laboratory of Systematic and Evolutionary Botany; Institute of Botany; Chinese Academy of Sciences; Beijing 100093 China
2. Graduate School of the Chinese Academy of Sciences; Beijing 100039 China
3. College of Life Science, Shanxi Normal University; Linfen, Shanxi 041004 China
4. Chengdu Institute of Biology; Chinese Academy of Sciences; P.O. Box 416 Chengdu, Sichuan 610041 China
5. Missouri Botanical Garden; P.O. Box 299 St. Louis, Missouri 63166-0299 U.S.A.