Udo talks with Dr. Callaway, an internationally renowned plant and community ecologist, who was one of three Montanans on a prestigious short-list of “The World’s Most Influential Scientific Minds”. Callaway has focused his international research of the past three decades on the interactions within plant communities and ecosystems. Research from his UM laboratory indicates that when humans introduce some plant species to new regions they force together species with different evolutionary trajectories from different continents, disrupting communities but also providing opportunities to test long held ecological paradigms. The conversation provides insight into how plants have moved across the globe, resulting in direct and indirect interactions between plants and with other organisms, including resource competition, and interactions with invasive species, as well as soil microbe, herbivore and competitor-mediated interactions. Callaway shares how other countries deal with invasive plant species and why it is important for a community to have an ecological knowledge base and talks about how his laboratory at UM developed ideas that have been a game changer in plant ecology and ending with some mysteries that remain in the field of global ecology.