Mucina, Ladislav, Iluka Chair in Vegetation Science and Biogeography, School of Plant Biology, The University of Western Australia, 35 Stirling Highway, Crawley WA 6009, Perth, Australia. Department of Geography & Environmental Studies, Stellenbosch University, Private Bag X1, Matieland 7602, Stellenbosch, South Africa. Department of Botany and Microbiology, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia.