1 Biological Sciences, University of Cape Town, Cape Town, South Africa; North Willamette Research and Extension Center, Department of Horticulture, Oregon State University, Corvallis, OR, USA. Electronic address: lloyd.nackley@oregonstate.edu.
2 Biological Sciences, University of Cape Town, Cape Town, South Africa.
3 Botany Department, Rhodes University, Grahamstown, South Africa; South African National Biodiversity Institute, Cape Town, South Africa.
4 Biological Sciences, University of Cape Town, Cape Town, South Africa; South African Environmental Observation Network, Pretoria, South Africa.