Gideon Smith is a well-known authority on succulent plants and author of several books. He is a professor of botany at the University of Pretoria. Ben-Erik van Wyk is a professor of botany at the University of Johannesburg, South Africa. His scientific field of interest is in plant classification, ethnobotany, and useful plants.
Help[s] to make sense of what sometimes seems an indigestible and - certainly to northern temperate gardeners - alien group of plants. -- Nick Macer Gardens Illustrated 20090428