The symbiosis of plants with arbuscular mycorrhizal fungi is ancient and dates back to the earliest land plants. In this marriage, the fungus extracts carbohydrates from the plant but delivers nutrients such as phosphate in return. This symbiosis does not only influence the chemical composition of the plant roots, which host the fungus, but can also affect the metabolites of the leaves. We could demonstrate that the chemical fingerprint of the leaves differs highly species-specifically between different plant species that are mycorrhized by the same fungus. Although all five investigated plant species share between 18 and 45% of their metabolites, only a very low percentage of metabolites responds in the same direction to mycorrhiza. This may be explained by the long time of cooperative engineering [epigenetics] of the individual plant species with the fungus.