Uncovering the cycad taxa ( Encephalartos species) traded for traditional medicine in Johannesburg and Durban, South Africa

Abstract

The bark and stems of Encephalartos species are used for traditional medicine across South Africa, and some species are traded in traditional medicine markets. The absence of characteristic plant parts such as leaves and cones in the chopped up market material presents a major challenge to the identification of the species traded. In this study, South Africa's two largest traditional medicine markets, Faraday in Johannesburg and Warwick in Durban, were surveyed to ascertain the source areas and species of Encephalartos in trade. Samples of stem fragments were purchased from vendors, identified to probable species and their stem diameter size class distributions determined using a specially designed size class chart. Species identification was undertaken by comparing trader citations of harvesting areas with the distributions of Encephalartos species in the province of KwaZulu-Natal (since all the specimens originated from KZN). The species most commonly recorded in the markets were identified as Encephalartos natalensis, E. villosus and E. ghellinckii; small quantities of what are likely to be E. ferox and E. senticosus were also observed. Following this study, the total number of South Africa's 37 Encephalartos species recorded as being used for traditional medicine is 25. Stem diameter size class distributions showed that most stem fragments came from sub-adult and adult cycads. Large arborescent species appear to be harvested by removing bark strips from adult individuals, while smaller arborescent and subterranean species are harvested by removing the entire plant. Regression relationships between stem tissue type and stem diameter for E. natalensis and E. ghellinckii indicate a strong, positive linear relationship of leaf base length and pith radius with stem diameter. Overall, this is the first known study that attempts to identify the cycad species traded in South African traditional medicine markets in conjunction with the size classes of the specimens in trade.