Until the emergence of the Convention on Biological Diversity in 1992 and the FAO Treaty on Plant Genetic Resources in 2001, opinion had hardened in some quarters that the principle of a common heritage of mankind regulated international transfer of plant genetic resources. By a historical analysis of customary international law in the colonial age and the recent pedigree of the principle of common heritage, this article points out the fallacies in such arguments and contends that plants have always been subject to various national jurisdictions. It has to be conceded, however, that contemporary developments in the field of international law relating to plant genetic resources foretell the emergence of a regime of multilateral relationships governing access to plant genetic resources. If it is to depart from its unfortunate history, such a regime of multilateral co-operation would have to pay serious regard to the issue of equitable access to and sustainable use of plant genetic resources.