In the middle of the twentieth century, a flurry of scientific sub-disciplines emerged. These went by the name of ethno-sciences and they came in numerous varieties from ethno-medicine to ethno-botany, -zoology, -biology, -medicine, -pharmacology, -astronomy, -psychology, -cartography, and more. The creation of these sub-disciplines was not, however, a strictly twentieth-century phenomenon. The development of “ethno-science” as an epistemic category that, in one way or another, involves other knowledges than science has a much longer and uneven history. This Special Focus Section aims to provide a critical historical account of the emergence of the “ethno-sciences,” largely focusing on the plant sciences as a paradigmatic example. In particular, it focuses on the ruptures and continuities that occurred from the late eighteenth through to the twentieth centuries, when Western scientists’ attitudes to the category of “Indigenous knowledge” were subject to change across space and time.