ABSTRACT

The introduction of alien plant species to tropical Africa dates as far back as the fifteenth century when the first Europeans arrived on the shores of the continent. Many of the species that were intentionally or unintentionally introduced today constitute a major proportion of the food, fibre, and wood resources on the continent

(Juhé-Beaulaton 1994; Wild 1968). But not all the introduced species were beneficial, as quite a number of them turned out to be noxious. Indeed, active and passive introductions of new species to the continent of Africa and around the world have continued throughout the centuries, and will continue for many more to come. There is a common belief that the twenty-first century will experience the most introductions of alien species, both plants and animals, to nonnative habitats as a result of globalization and increased international trade. The continent of Africa is both a major donor and recipient of alien genetic resources, which sooner or later become unwanted or invasive in their new environments.