 Calostoma cinnabarinum was thought to be saprotrophic , and has been described in this manner in both scholarly and popular discussions of the species . However , this classification was the result of its taxonomic history and comparisons with saprotrophic fungi that are not closely related . After its assignment to the Sclerodermatineae , a suborder whose members are ectomycorrhizal , its ecological role came into question . In 2007 , Andrew Wilson and David Hibbett of Clark University and Eric Hobbie of the University of New Hampshire employed isotopic labeling , DNA sequencing , and morphological analysis to determine that this species is also ectomycorrhizal . Like all mycorrhizal fungi , C. cinnabarinum establishes a mutualistic relationship with the roots of trees , allowing the fungus to exchange minerals and amino acids extracted from the soil for fixed carbon from the host . The subterranean hyphae of the fungus grow a sheath of tissue around the rootlets of the tree . This association is especially beneficial to the host , as the fungus produces enzymes that mineralize organic compounds and facilitate the transfer of nutrients to the tree . The only host trees identified for C. cinnabarinus are Quercus oaks , although related members of Calostoma have been observed to associate with other trees in the Fagaceae family , such as beech . 
