Ectomycorrhizal , Amanita muscaria form symbiotic relationships with many trees , including pine , spruce , fir , birch , and cedar . Commonly seen under introduced trees , A. muscaria is the fungal equivalent of a weed in New Zealand , Tasmania and Victoria , forming new associations with southern beech ( Nothofagus ) . The species is also invading a rainforest in Australia , where it may be displacing the native species . It appear to be spreading northwards , with recent reports placing it near Port Macquarie on the New South Wales north coast . It was recorded under silver birch ( Betula pendula ) in Manjimup , Western Australia in 2010 . Although it have apparently not spread to eucalypts in Australia , it have been recorded associating with them in Portugal .