Career
From the age of 18, he was associated with the botanical garden in the city of Avignon. He performed extensive studies of flora native to Corsica and in the environs of Mont Ventoux. During his lifetime, he amassed an herbarium of 300,000 specimens.
In the fields of conchology and palaeontology, he conducted collecting expeditions to the Pyrenees, Catalonia and Italy.
The natural history museum, Musée Requien, in Avignon is named in his honor. He is taxonomic authority of the plant genus Helxine (family Urticaceae).
The genera Requienella (author Jean-Henri Fabre) and Requeinia (author Augustin Pyramus de Candolle) are named after him, as are plants with the specific and subspecific epithets of requienii.