14 15 Eryngium viviparum (Apiaceae) is an endangered endemic plant of the Atlantic region of Europe, 16 growing in seasonally flooded sites. The species is characterized by a highly disjunct distribution. 17 Indeed, it occurs only in a few sites in the NorthWest part of the Iberian Peninsula and in a single 18 locality in France. In order to improve the conservation status of Eryngium viviparum in France, a 19 conservation program has been implemented, which plans reintroduction actions. Before considering 20 such an operation, genetic studies are conducted in order to determine the genetic status of the last 21 French population and to identify the genetic source that should be considered for the best 22 reintroduction strategy. Using microsatellite markers, we documented the genetic structure of the last 23 French population, and compared its genetic diversity with ten Iberian populations, which cover the 24