His botanical career began very early. At 18, he penned a work on the local flora of the Haute-Saône, currently on display at the Natural History Museum of Gray. He collected plants for study in Algeria and Morocco between 1902 and 1904. After obtaining his PhD in 1905, he was a professor of botany at the Faculty of Sciences in Algiers starting in 1911 where he specialised in phytopathology. He was put in charge of botanical research by the Moroccan government and was responsible for botanical studies in the Central Sahara. He was a member of a number of institutions, including the Société mycologique de France and the Société d'histoire naturelle de la Moselle based in Metz, which he joined in 1897 at the start of his career. He was the author of numerous works, including important contributions between 1918 and 1931 on the flora of North Africa. He ended his career as the Rector of the University of Algiers. His magnum opus was The Flora of North Africa, a 16-volume work published posthumously in 1953.
Named species
Among species he named or renamed are:
Amanita codinae Singer
Argyrocytisus battandieri Raynaud
Campanula monodiana Maire
Gymnopilus sapineus Maire
Hygrophoropsis aurantiaca Maire
Hygrophorus reai Maire
Hypomyces vuilleminianus Maire
Laccaria bicolor P.D. Orton
Lentinellus vulpinus Maire & Kühner
Psathyrella candolleana Maire
Psathyrella hydrophila Maire
Xeromphalina campanella Maire & Kühner
He also erected the family Paxillaceae, noting its affinities with boletes, in 1902, based on anatomical similarities. This was confirmed many years later by molecular studies firmly placing the genera Paxillus and Gyrodon at the base of the clade containing the members of the genus Boletus.
Legacy
The French Academy of Sciences awarded him the Prix Montagne for 1903. Several species were named in his honour, including fungi such as the beechwood sickener, René Maire's ringless Amanita from Egypt, Clitocybe mairei, Conocybe mairei, Clavicorona mairei, Cortinarius mairei, Galerina mairei, Hemimycena mairei, and Lactarius mairei, among others, as well as some North African plants such as the ornamental grass Atlas fescue. The genus Mairetis is also named after him. Species names for Maire typically end in .
