The functions of hedges are not permanent : they are linked with the agrarian systems and the evolution of the society. The comparison between the hedges built in England during the enclosures and the traditional hedges of Western France shows it. The first were used to divide fields in order to practise particular rotations of crops, the others to protect crops from the livestock, and they were built by the farmers for whom they were useful. But they also have many other functions which derive from their existence, particularly ecological functions. Now, hedges have widely lost their original office and their secondary functions appears essential : hedges seem less useful to the farmers (who often neglect to maintain them) than to other people. This transfer of the functions of the hedge necessarily involves a change of the aspect of the landscape.