1. Unit for Environmental Sciences and Management, Department of Botany, North-West University, Mafikeng, Private Bag X 2046, Mmabatho 2735, South Africa
2. School of Mathematics, Sciences and Technology Education, Department of Natural Sciences, North-West University, Mafikeng, Private Bag X 2046, Mmabatho 2735, South Africa
3. South African National Biodiversity Institute, Pretoria National Botanical Garden, 2 Cussonia Avenue, Brummeria, Silverton 0184, South Africa
4. Centre for Functional Biodiversity, School of Life Sciences, University of KwaZulu-Natal, P/Bag X01, Scottsville, Pietermaritzburg 3209, South Africa