Fly agaric fungus (Amanita muscaria). The mycelium of the fly agaric fungus shares a symbiotic relationship with the spruce, forming a mycorrhizal sheath around the roots of the tree. This is a mutualistic relationship, with the fungus helping its host to extract nutrients and water from the soil, in return for sugars via the plant's photosynthesis. This fungus is hallucinogenic and poisonous. The genus Amanita is recognized by its swollen basal volva and the ring on its stem.