1. Department of Botany, National Museum of Natural History, Smithsonian Institution P.O. Box 37012, MRC-166 Washington, DC 20013-7012 U.S.A.
2. Department of Biological Sciences, George Washington University, 2023 G Street, N.W. Washington, DC 20052 U.S.A.
3. Laboratories of Analytical Biology, National Museum of Natural History, Smithsonian Institution Suitland, Maryland 20746 U.S.A.