1. Department of Botany and Zoology, Centre for Invasion Biology, Private Bag X1, Stellenbosch University, Matieland 7602, South Africa
2. Natural Resources and the Environment, CSIR, P.O. Box 320, Stellenbosch 7599, South Africa
3. Agroforestry Enterprises, Villebeuf, Cussy en Morvan 71550, France