Biological invasions are a major threat to biodiversity, and The ecology of invasions by animals and plants by Charles Elton (1958) is often recognized as the starting point for modern invasion research. Yet there were predecessors in invasion research whose contribution to the development of ideas and concepts in this field is often underestimated.
To contribute to a balanced perception of pioneers in invasion research, we retrace the work of the Swiss botanist Albert Thellung (1881-1928) whose main work, La flore adventice de Montpellier, appeared 100 years ago, in 1912, and illustrate how his ideas contributed to the current state of the art in the fields of invasion science and biogeography.