I found three different Oak Trees on the same day and took these photos of the Beef steak Fungi (Fistulina hepatica). The fungi were in different stages of growth, the last picture, showing it removed from the tree was taken several weeks later when i had felt that the fungi had spored, I took it home and cooked it in the frying pan, It was quite tasty. All of the fungi fruiting bodies grew from exposed seasoned wood, usually a branch stub on a otherwise healthy looking Tree. I have seen Fistulina growing on many Trees but i have never yet seen a tree die that had a Fistulina infection, although i have seen many Trees cut down by ignorant Arboriculturists claiming that the Tree is dangerous !!. ( just for the money ) The worst case i have ever seen was when the two guys in charge of street Trees in pompey (1997) cut down a yew Tree in a park because it showed a Fruiting body of Fistulina, the yew Tree had the biggest girth of any Yew i had seen in the flesh, and they called themselves Arbs. ( because of the way they grow, Yew Trees are virtually indestructable to all Heart rots )