In 2014, Crypsis schoenoides (L.) Lam. was discovered in the natural region of Dombes (Ain, Auvergne-Rhône-Alpes, France). It was observed in an artificially fish pond, traditionally and extensively exploited (annual drying without cultivation or amendment). In the administrative region Auvergne-Rhône-Alpes, it was the first observation of this Mediterranean and Atlantic species. The French distribution of this rare and locally protected/threatened species is presented. A phytosociological comparison of the vegetation sheltering the dombist population with the vegetation present in France known to shelter this species is carried out. The results show that the dombist population of C. schoenoides has become integrated into a continental vegetation (Eleocharito ovatae-Caricetum bohemicae Klika 1935, Eleocharition soloniensis G. Phil. 1968). However, the other French vegetations known to harbour C. schoenoides are attached to the Heleochloion schoenoidis Braun-Blanq. ex Rivas Goday 1956, a Mediterranean and Atlantic alliance. Theses elements, the biology of Crypsis genera as well as discussions with the fish farm staff and the Conservatoire botanique national alpin, tend to favour the hypothesis of a human introduction of Crypsis schoenoides in this Dombist pond.