Jean-Baptiste Caumeil, known as Brother Héribaud-Joseph (1841-1917), was a French Brother of the Christian Schools. He was the author of various works in Botany, including the Flora of Auvergne and the Muscinea of Auvergne, and made new discoveries in paleobotany, particularly concerning the fossil data on diatom taxa. In the years 1880-1900, several Brothers of the Christian Schools were botanists and they collaborated with Brother Heribaud-Joseph. In this communication, we shall synthesize the works of some of these Brothers who were in relationship with Brother Héribaud-Joseph and who had to leave France for South America during the abolition of congregations and public establishments of religion in France in 1904-1905. We shall particularly consider Brother Arsène Brouard’s papers (known as Brother Gerfroy-Arsène, 1867-1938), in which he introduced a systematic study of the Mexican Flora. We shall also glance at Jean-Sylvestre Sauget’s research (known as Brother Quadrat-Léon, 1871-1955), who explored the botanical resources in Cuba. In this paper, we try to understand the meaning of their research.