450 million years ago, the first plants left aquatic life. Researchers from the CNRS and the Université de Toulouse III—Paul Sabatier, in collaboration with INRAE, have succeeded in demonstrating that this colonization of land by plants was made possible by a partnership between plants and fungi. Validating this 40-year-old hypothesis allows us to understand a stage that was crucial to the development of life on Earth. The study is published in Science on 21 May 2021.