Phenotypic and Growth Stage Development Data of a Quercus robur Mycorrhization Experiment

In this experiment, we investigated the inoculation-effects of two ectomycorrhizal fungi (EMF) species with contrasting evolutionary histories, ecological properties, host-preferences, and habitat-ranges on phenotypic responses and growth dynamics of pedunculate oak (*Quercus robur*), an ecologically and economically important temperate forest tree species. We set up the mycorrhization experiment using 96 plants of a genetically uniform *Q. robur* clone (DF159) and applied four treatments: A control treatment; an inoculation-treatment with the cosmopolitan Ascomycete *Cenococcum geophilum*, which is commonly found in oak forests; an inoculation-treatment with the Basidiomycete *Piloderma croceum*, which has not yet been found in natural oak forests but has been shown in previous experiments to support oak growth; and a co-inoculation treatment. We then assessed growth stage development of the trees over eight experimental weeks and measured various phenotypic traits during a destructive sampling.