▁associate ▁with ▁e ct omy cor rh iz al ▁fung al ▁species . ▁These ▁latter ▁associations ▁are ▁often ▁called ▁tri part ite ▁associations ▁as ▁they ▁involve ▁the ▁orch id , ▁the ▁e ct omy cor rh iz al ▁fung us ▁and ▁its ▁photos yn th etic ▁host ▁plant . ▁Some ▁of ▁the ▁challeng es ▁in ▁determ ining ▁host - specific ity ▁in ▁orch id ▁my cor rh iz ae ▁have ▁been ▁the ▁methods ▁of ▁ident ifying ▁the ▁orch id - specific ▁fung i ▁from ▁other ▁free ▁living ▁fung al ▁species ▁in ▁wild - s our ced ▁samples . ▁Even ▁with ▁modern ▁mole cular ▁analysis ▁and ▁genom ic ▁databases , ▁this ▁can ▁still ▁prove ▁difficult , ▁partially ▁due ▁to ▁the ▁difficulty ▁in ▁cult uring ▁fung i ▁from ▁proto c orm s ▁and ▁identification ▁of ▁fung al ▁samples , ▁as ▁well ▁as ▁changes ▁in ▁evol ving ▁r D NA . ▁However ▁it ▁has ▁become ▁clearer ▁that ▁different ▁fung i ▁may ▁associate ▁with ▁orch ids ▁at ▁specific ▁stages , ▁whether ▁at ▁germ ination , ▁proto c orm ▁development , ▁or ▁throughout ▁the ▁orch id ' s ▁life . ▁The ▁types ▁of ▁orch ids ▁and ▁their ▁sym bi otic ▁fung i ▁also ▁vary ▁depending ▁on ▁the ▁environmental ▁nich es ▁they ▁occup y , ▁whether ▁terrest rial ▁or ▁growing ▁on ▁other ▁plants ▁as ▁an ▁e pi phy te . ▁ ▁E ct omy cor rh iz al ▁Bas idi om yc ota ▁ ▁A ▁number ▁of ▁other ▁bas idi om yc et ous ▁fung i ▁have ▁been ▁documented