1. Department of Environmental and Plant Biology; Ohio University; Athens, Ohio 45701 U.S.A.
2. Authors are listed alphabetically, except for the first and last authors
3. Section of Evolution and Ecology; University of California; Davis, California 95616 U.S.A.
4. UBC Botanical Garden and Centre for Plant Research, 6804 SW Marine Drive; The University of British Columbia; Vancouver, British Columbia Canada V6T 1Z4
5. Department of Botany; University of Florida; Gainesville, Florida 32611-8526 U.S.A.
6. Department of Biology; P.O. Box 355325, University of Washington, Seattle, Washington 98195-5325 U.S.A.
7. Florida Museum of Natural History; University of Florida; Gainesville, Florida 32611 U.S.A.
8. Department of Ecology & Evolutionary Biology and Peabody Museum of Natural History; Yale University; P.O. Box 208106, New Haven, Connecticut 06520-8106 U.S.A.