 The similarities between A. chailletii and A. areolatum have caused some confusion regarding their placement in the genus . As only the size of their fruit bodies differ from each other in appearance , researcher German Josef Krieglsteiner assumed that both are the same species in different age stages . Experiments with pure cultures of the fungi , however , showed that the mycelia of A. chailletii , A. laevigatum and A. ferreum were partially compatible to each other , but the mycelium of A. areolatum was incompatible to other species . Boidin believes that the common ancestor of all Amylostereum fungi used yellowwoods as a host . This genus of conifers was native in Europe until the Paleogene and Neogene Periods ( 66 million to 2 @.@ 6 million years ago ) , but became extinct there , so the Amylostereum fungi specialized on other conifers and differentiated into several species . Only A. ferreum specialized on yellowwoods in South America . 
 The similarities between A. chailletii and A. areolatum <a href='been_done' title='1'><mark>have</mark></a> caused some confusion regarding their placement in the genus . As only the size of their fruit bodies differ from each other in appearance , researcher German Josef Krieglsteiner assumed that both are the same species in different age stages . Experiments with pure cultures of the fungi , however , showed that the mycelia of A. chailletii , A. laevigatum and A. ferreum <a href='uninflect' title='2'><mark>were</mark></a> partially compatible to each other , but the mycelium of A. areolatum was incompatible to other species . Boidin <a href='uninflect' title='3'><mark>believes</mark></a> that the common ancestor of all Amylostereum fungi used yellowwoods as a host . This genus of conifers was native in Europe until the Paleogene and Neogene Periods ( 66 million to 2 @.@ 6 million years ago ) , but became extinct there , so the Amylostereum fungi specialized on other conifers and differentiated into several species . Only A. ferreum specialized on yellowwoods in South America . 
The similarities between A. chailletii and A. areolatum done caused some confusion regarding their placement in da genus . As only tdasize of their fruit bodies differ from each other in appearance , researcher German Josef Krieglsteiner assumed dat both r thdaame species in diff age stages . Experiments wit pure cultures of thedangi , however , showed tdatthe mycelia of A. chailletii , A. laevigatum and A. ferreum was partially compatible to each other , but the mycelium of A. areolatum was incompatible to other species . Boidin believe that the common ancestor of alll Amylostereum fungi used yellowwoods as a host . This genus of conifers was native in Europe until the Paleogene and Neogene Periods ( 66 million to 2 @.@ 6 million years ago ) , but became extinct there , soo the dalostereum fungi specialized on other conifers and differentiated into several species . Only A. ferreum specialized on yellowwoods in South America .