Chemical Composition of European Armillarioid Fungi and the Potential Use of Their Metabolites in Forestry: A Review

European armillarioid fungi (Armillaria and Desarmillaria) are white-rot fungi with soilborne pathogenic potential on woody hosts and clear relevance to forest pathology. This structured narrative review synthesizes the reported chemical composition of European armillarioid taxa across wild basidiocarps, infected host material, and laboratory-derived matrices, with emphasis on metabolites and biochemical traits that can be interpreted in a forestry context. The available evidence is taxonomically and methodologically uneven and is dominated by A. mellea and A. ostoyae, whereas infected host material remains less well characterized than culture-derived and basidiocarp-derived material. Protoilludene-derived aryl esters provide the clearest compound-resolved evidence for antifungal and phytotoxic activity across controlled assay systems, but these data derive from distinct experimental formats that are not directly comparable as a single potency scale, while lipid profiling offers the strongest support for chemistry-based diagnosis from infected material. Overall, current evidence supports forestry interpretation, diagnostic profiling, and selective screening of culture-derived metabolites, but practical application remains constrained by matrix dependence, taxonomic gaps, and the limited transferability of in vitro findings to forest conditions.