A joint field trip of CBNA and CJBG  was organized at the end of July 2017 in the area of Zermatt, especially looking for Trifolium saxatile All. Sweet clover (Felsenklee, trèfle des rochers, trifoglio dei greti) is a pioneer heliophilous sub-alpine to alpine species . It grows mostly on sandy-gravelly alluvial soils on the edges of torrents and on recent moraires. This uncompetitive species depends on particular conditions (torrential erosion, landslide dynamic) to maintain an open environment. Consequently, it has a very limited potential habitat in the Alps and is listed as “vulnerable” in Switzerland. In this country, it is endemic to the Vispvalleys region (Zermatt, Saas Fee) and distributed between 1400 and 2700 m. above sea level. In a splendid landscape under the Gornergrat, at the edge of the Gorner glacier, one quite large population has been identified and described. Leaf samples were taken for DNA analysis in Gap-Charance and seeds harvested for cold storage in Geneva. We could collect some other species in this area during this trip.