Not a true polypore! In the Russulales. Has ridged and spiny round pores like russulas and lactarius. True polypores have cylindrical or elliptical smooth spores. Pores are angular. Pore surface runs down stem and doesn't stain or bruise. White flesh. Grows at the base of deciduous trees, especially oaks. Gets quite large, up to three feet! Parasitic causing stringy butt rot of the heartwood. Also saprobic at base of dead trees. Edible when young.