The rusts are highly specialised obligate parasites of flowering plants, conifers and ferns. The cereal rusts are amon the most destructive pathogens of economic plants ... Fungi: An Introduction (1960)
Polyporus is a large genus of which one of the best known species is P. betulinus, a destructive parasite of birch, but including also species parasitic on economically valuable trees, such as oak, beech and many conifers. Fungi: An Introduction (1960)