Over the last few years, six supposed cases of particular arrangements of trees, shrubs or posts have been studied with the help of Earth and life sciences. Two sites have been identified as “sacred groves”, one Gaulish and the other Gallo-Roman. In four other cases, one of them in a Gallo-Roman sanctuary, the interpretation proved more complex, or even unconnected with any human activity. This study affords the opportunity to compare the methods used and the results obtained, as well as an assessment of what these results might contribute to the characterization of supposed ritual contexts. This subject exemplifies the problematics that encompass archaeology stricto sensu – i.e. the study of man-made artefacts – and archaeo-sciences based on natural evidence such as identifiable particularities of flora, fauna and soil tracers. The subsequent conclusions encourage the application of these research methods to certain other contexts, i.e. four hearths and ten enclosure ditches. Traduction : Margaret & Jean-louis CADOUX.