1. Institute for Systematic Botany, University of Zurich, CH-8008 Zurich, Switzerland
2. Present address: Department of Biochemistry, University of Stellenbosch, Private Bag X1, Matieland 7602, Stellenbosch, South Africa
3. Molecular Ecology and Systematics Group, Department of Botany, Rhodes University, Grahamstown 6140, South Africa