Hewett Cottrell Watson and Edward Forbes were two naturalists of the Victorian age. They were protagonists on a dispute that generated comment and serves as an illuminating case study of misunderstanding in priority issues. Watson accused Forbes of having plagiarized his original classification of the British plants into groups on the basis of their geographical distribution. This controversy originated mostly from a so-far-ignored basic difference in Watson’s and Forbes’ ideas about biogeographical regionalization. Watson’s classification of the British flora into groups (...) of species with similar distribution was probably the first application of the concept of “regional chorotype.” By contrast, the biogeographical classification of the British flora proposed by Forbes belongs to the concept of “element,” because it was based on assumed species history (i.e. colonization routes). The two approaches may produce similar outcomes, but remain conceptually different. Although personal reasons may have contributed to exacerbate the Watson–Forbes controversy, failure in recognizing this distinction by its actors and their contemporaries, such as Hooker and Darwin, was the most important cause. (shrink)