We provide a detailed description of an interleaved and heavily annotated copy of Florae Berolinensis Prodromus, a flora of Berlin published by the German apothecary and botanist Karl Ludwig Willdenow in 1787, which today is preserved at the Staatsbibliothek zu Berlin – Preußischer Kulturbesitz. We demonstrate that this is the copy that the author himself used and carried with him during his botanical excursions in and around Berlin to prepare a second edition of the work. By analyzing this document as (...) paper technology, we reveal that even seemingly trifling aspects of its material organization enabled far-reaching biological research agendas that were not originally intended. The hybrid form of manuscript and printed book, used in field excursions, enabled a kind of natural-historical observation that was at once detailed and bound by strict convention, a combination that inadvertently opened new research questions and suggested new objects of research. We thereby contribute to an understanding of the history of natural history that goes beyond the history of ideas and the intended uses of techniques, giving an example of how routine work on paper within a scientific tradition could generate innovation. (shrink)