The Great Site of the Gorges du Tarn, Jonte, and Causses extends over 50,000 acres (20,000 ha) and 19 municipalities. Like the thirty or so Great Sites of France, the Gorges are listed under the law of May 2, 1930, on the protection of natural monuments and sites of artistic, historical, scientific, legendary or picturesque character. The Gorges du Tarn, Jonte, and Causses, therefore, are managed by the Ministry of the Environment as part of a national policy for the protection and enhancement of these major sites. They constitute a space sheltering unique vegetation and recognized since 1999 as one of the most remarkable sites in France to find the Venus hoof, a plant that usually only flowers once or twice a year.