1. Smithsonian Institution; Department of Botany; National Museum of Natural History; Washington, D.C. 20013-7012 U.S.A.
2. Laboratory of Molecular Systematics; Botanic Institute of Barcelona (CSIC-ICUB); Passeig del Migdia, s.n. Barcelona 08038 Spain
3. Molecular Ecology and Systematics Group; Department of Botany; Rhodes University; Grahamstown 6140 South Africa
4. Institute of Systematic Botany; University of Zurich; Zollikerstrasse 107 Zurich 8008 Switzerland