This article recounts the main orientations in the life and thought of Brother Marie-Victorin (1885-1944). A member of the Frères des écoles chrétiennes, he was also a botanist, and the author of the Laurentian flora. He sought to position his work with respect to the theory of evolution. After some initial publications opposed to Darwinism, his observations and studies in the 1920s provided evidence for an evolutionary interpretation of the biogeographic distribution of the flora in Quebec. In addition, his trip to the meeting of the British Association for the Advancement of Science held in Cape Town in 1929 allowed him to meet first Father Breuil, and later Canon Grégoire. He subsequently developed his arguments about the evidence of evolution to be found in the flora of Northeastern America. His vision of evolution was not, however, strictly speaking Darwinian but was informed by various currents of thought present at the beginning of the twentieth century : mutationism (Hugo De Vries), the thought of Teilhard de Chardin and the points of view of the scientists in Louvain.