1. Department of Biology, University of Florida, Gainesville, Florida 32611‐8525 USA
2. Department of Ecology and Evolutionary Biology, Brown University, Providence, Rhode Island 02912 USA
3. Florida Museum of Natural History, University of Florida, Gainesville, Florida 32611‐7800 USA
4. Department of Botany, National Museum of Natural History, Smithsonian Institution, Washington, D.C. 20013‐7012 USA
5. Department of Forest Ecology and Biogeosciences & Stillinger Herbarium, University of Idaho, P. O. Box 441133, Moscow, Idaho 83844‐1133 USA
6. Department of Plant Sciences, University of Cambridge, Cambridge, CB2 3EA, UK
7. Department of Biology, University of Washington, Seattle, Washington 98195‐5325 USA
8. Department of Botany, University of Wisconsin, Madison, Wisconsin 53706 USA
9. Biology Department, Oberlin College, Oberlin, Ohio 44074‐1097 USA
10. Department of Biological Sciences, Eastern Illinois University, Charleston, Illinois 61920 USA
11. Department of Biological Sciences, University of New Orleans, New Orleans, Louisiana 70148 USA
12. Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061 USA
13. Département de Biologie Végétale, Université Cheikh AntDeara Diop, Dakar–Fann, BP 5005, Republic of Sénégal
14. Department of Organismic and Evolutionary Biology, Harvard University Herbaria, 22 Divinity Avenue, Cambridge, Massachusetts 02138 USA
15. Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan 48109‐1048 USA
16. Department of Ecology and Evolutionary Biology, University of Arizona, 1041 East Lowell, Tucson, Arizona 85721‐0088 USA
17. Department of Ecology and Evolutionary Biology, Yale University, P. O. Box 208106, New Haven, Connecticut 06520‐8106 USA