1. Botany Department; The Field Museum; 1400 South Lake Shore Drive Chicago, Illinois 60605 U.S.A.
2. Key Laboratory of Biodiversity and Biogeography; Kunming Institute of Botany, Chinese Academy of Sciences; Graduate School of Chinese Academy of Sciences; Kunming, Yunnan Beijing 650204 100039 P. R. China P. R. China
3. School of Science; Osaka Prefecture University; Sakai, Osaka 599-8531 Japan
4. Key Laboratory of Biodiversity and Biogeography; Kunming Institute of Botany, Chinese Academy of Sciences; Kunming, Yunnan 650204 P. R. China
5. Department of Botany; Charles Darwin Research Station; Isla Santa Cruz, Galápagos Ecuador
6. Department of Botany; MRC-166 Smithsonian Institution; P.O. Box 37012 Washington, D.C. 20013-7012 U.S.A.