Bondarzewia berkeleyi, commonly known as Berkeley's polypore, or stump blossoms, is a species of polypore fungus in the family Russulaceae. It is a parasitic species that causes butt rot in oaks and other hardwood trees. A widespread fungus, it is found in Africa, Asia, Europe, and North America. Elias Magnus Fries described the species as Polyporus berkeleyi in 1851. It was moved to the genus Bondarzewia in 1941.