Situated at the intersection of the social history of science, transimperial history, and environmental history, this thesis examines the consequences of the industrialization of drug production on the ways medicinal plants are used. Drawing from the under-studied archives of the pharmaceutical industry and other scientific institutions, this research highlights that plants were an essential component of the drugs mass-produced by pharmaceutical companies starting in the 1880s. Building on recent developments in trans-imperial history, it intersects the trajectory of the German Empire with those of the British and French empires to prove that plants, far from being confined to the anachronistic sphere of 'alternative medicines', remained strategic resources in the 20th century, leading to major rivalries among Western empires to control their supply on a global scale. In 1944, the Allies immediately appropriated the stocks of medicinal plants requisitioned by the Germans from French peasants. Supporting its argument, this thesis employs digital history, particularly mapping, to trace the evolution of the international trade in plants, while offering an analysis of the environments in Germany that enabled their cultivation, in an interdisciplinary approach combining the contributions of history, geography, and environmental sciences.