Having authored or co-authored over 50 books, and hundreds of scientific and popular papers, Gideon F. Smith is South Africa's most prolific author on succulents of the Old and New Worlds. He also has a keen interest in landscaping, gardens, and gardening. He is an Honorary Professor at the Nelson Mandela University, Port Elizabeth, South Africa, and a research associate at the University of Coimbra in Portugal.With a keen interest in the African flora and the succulents of the world, Estrela Figueiredo has authored or co-authored several hundred scientific and popular papers, and numerous books on aspects of the botany of the continent. She also has a keen interest in sustainable gardening. She is an Honorary Professor at the Nelson Mandela University, Port Elizabeth, South Africa, and a research associate at the University of Coimbra in Portugal.A plant taxonomist by training, but with a wide interest in the biodiversity of southern Africa, Abraham E. [Braam] van Wyk is an Emeritus Professor with more than 40 years of service to the University of Pretoria. He is a prolific researcher, and has authored or co-authored numerous publications on the botany of southern Africa, including several popular-scientific books on the wild flowers and trees of the region.