1. 2The Lewis B. and Dorothy Cullman Program for Molecular Systematics Studies, The New York Botanical Garden, Bronx, New York 10458–5126 USA;
2. 3Molecular Systematics Section, Jodrell Laboratory, Royal Botanic Gardens, Kew, Richmond, Surrey, TW9 3DS, UK;
3. 4University of Michigan Herbarium, North University Building, Ann Arbor, Michigan 48109–1057 USA;
4. 5Molecular Biology Building, Iowa State University, Ames, Iowa 50011–3260 USA