1. South China Botanical Garden; the Chinese Academy of Sciences; Guangzhou 510650 China
2. Graduate School of the Chinese Academy of Sciences; Beijing 100039 China
3. State Key Laboratory of Systematic and Evolutionary Botany; Institute of Botany; the Chinese Academy of Sciences; Beijing 100093 China
4. Biological Sciences; Graduate School of Science and Technology; Kumamoto University; Kurokami, Kumamoto 860-8555 Japan
5. East African Herbarium; National Museums of Kenya; Nairobi 00502 Kenya
6. Department of Botany; National Museum of Natural History; Smithsonian Institution; MRC166 Washington, D.C. 20013-7012 U.S.A.