1. Department of Plant Biology; Southern Illinois University; Carbondale IL 62901-6509 USA
2. Life Sciences, Plants Division; The Natural History Museum; Cromwell Road London SW7 5BD UK
3. Pennsylvania Natural Heritage Program; Western Pennsylvania Conservancy; 800 Waterfront Dr. Pittsburgh PA 15222 USA
4. Department of Earth and Environmental Sciences; Boston College Weston Observatory; 381 Concord Rd. Weston MA 02493 USA