South African plants growing wild in Mexico: patterns and the uncertainty of native areas

Background and aim: Understanding floristic exchanges between regions helps predict introduction and invasion processes. Of the about 700 introduced angiosperm species in Mexico, most are from the Old World, including Africa. This study focuses on the plants that migrated from South Africa to Mexico, two megadiverse countries of the Global South with comparable climates. It addresses the problems of determining native species, and also explores patterns of habit, life cycle, use categories and times of arrival. Methods: An exhaustive literature review identified the South African species growing wild in Mexico. A decision diagram outlines the inclusion/exclusion criteria; reasons for the decision on each species are provided. Data on habit, life cycle, uses and earliest herbarium specimen dates were compiled and analysed. Results and conclusion: Of the 129 species listed in databases and literature as native South African species in Mexico, only 43 were confirmed. Poaceae contributed 53% of the species. Perennial forbs and grasses dominated; there was only one shrub and no trees. Uses were documented for 88% of species, mainly as forage and ornamental. Few species used as food or medicine in South Africa were utilised similarly in Mexico. Most South African species arrived during the 20th century, likely via the USA and South America. The lack of secondary uses in Mexico suggest commercial introductions as the primary reason for arrival. The workflow proposed here could assist other countries of the Global South with the identification of the causes of species introductions, aiding prevention.