▁as ▁leaves , ▁tw igs , ▁b ark ▁and ▁branches . ▁It ▁accomplish es ▁this ▁by ▁producing ▁en zym es ▁capable ▁of ▁breaking ▁down ▁the ▁three ▁major ▁bio chem ical ▁components ▁of ▁plant ▁cell ▁walls ▁found ▁in ▁l itter : ▁cell ul ose , ▁hem ic ell ul ose ▁and ▁l ign in . ▁ ▁The ▁fruit ▁bodies ▁of ▁My c ena ▁incl in ata ▁grow ▁in ▁dense ▁groups ▁or ▁clusters ▁on ▁decay ing ▁hard wood ▁logs ▁and ▁st umps ▁( es pecially ▁o ak ▁and ▁ch est nut ) ▁during ▁the ▁spring ▁and ▁aut umn . ▁The ▁fung us ▁forms ▁a ▁white , ▁w ool ly ▁my cel ium ▁on ▁the ▁surface ▁of ▁decom pos ing ▁o ak ▁leaves . ▁Occ asion ally , ▁it ▁can ▁be ▁found ▁growing ▁on ▁a ▁living ▁tree . ▁In ▁eastern ▁North ▁America , ▁it ▁is ▁abund ant ▁in ▁the ▁area ▁bounded ▁by ▁Nova ▁Scot ia , ▁Ontario , ▁Man it oba , ▁Missouri , ▁North ▁Carolina , ▁and ▁New ▁York . ▁It ▁has ▁been ▁found ▁in ▁Oregon , ▁but ▁the ▁species ▁appears ▁to ▁be ▁generally ▁rare ▁along ▁the ▁Pacific ▁Coast . ▁The ▁range ▁of ▁the ▁fung us ▁also ▁includes ▁Europe , ▁the ▁Can ary ▁Islands , ▁North ▁Africa , ▁East ▁Si ber ia , ▁Japan , ▁M ales ia , ▁Turkey , ▁and ▁New ▁Zealand . ▁ ▁Chem istry ▁In ▁a ▁study ▁of ▁the ▁trace ▁metal ▁concentr ations ▁of ▁various ▁m ush rooms ▁species ▁found ▁in ▁Or du ▁( T ur key ), ▁M .  