We thank B. Brosi, D. Pistey-Lyhne, A. Prag, M. Roberts, E. Scott, A. Vega and E. Wilder for field assistance. We are also most grateful to the staff at the Las Cruces Biological Field Station of the Organization for Tropical Studies and the Rio Tigre Lodge for logistical support. We are deeply indebted to Ronald Liesner (Missouri Botanical Garden) for invaluable botanical instruction and plant identification. We also depended heavily on the generous assistance of Michael Grayum and Barry Hammel for plant identification. We received tremendous help with identifications of species in particular plant families from many experts from the Missouri Botanical Garden, Instituto Nacional de Biodiversidad (INBio) and the Cal Academy of Science, including: R. Aguilar, F. Alameda, C. Boggs, U. Chavarría, T. Croat, T. Daniel, G. Davidse, R. Evans, J. González, P. Hoch, P. Jorgensen, J. MacDougal, J. Miller, J. Morales, J. Solomon, K. Steiner, D. Stevens, P. Stevens, C. Taylor and N. Zamora. We are most grateful for financial support provided by Peter and Helen Bing, the Teresa Heinz Foundation, the National Science Foundation, the Winslow Foundation and Stanford University. We appreciate the many helpful comments on the manuscript from W. Cornwell, B. Brosi, E. Scott and two anonymous referees.