If you’ve seen a well-developed clinker polypore (inonotus obliquus) protruding from a tree, there’s a good chance that you remember it. This fungus causes large, black, cinder-like growths, sometimes neatly conical, but often rough and ragged. Also called the birch polypore, you can find these conks on all species of birch, as well as on hophornbeam and occasionally on other hardwoods. By the time the fungal tissue is visible on the outside, the inside of the tree is likely to be rotten to the core.
Much is yet to be learned about this organism, but it seems that infection often occurs after another fungus, called Nectria, has invaded a tree. Injuries, too, allow the clinker polypore to get a foothold, and once it has settled in, death – though sometimes a slow death – seems to be inevitable. » Continue Reading.