[Putative ID] Climacodon septentrionalis is usually impressive, forming massive clusters that can be seen from many yards away. At this distance it looks like a polypore, growing on dead hardwoods or from the wounds of living trees. But while it is officially in the order Polyporales, it has teeth on its underside, rather than pores, and is usually treated with the toothed mushrooms.
The fruiting bodies of Climacodon septentrionalis are extremely durable and can last for many weeks–long enough, in fact, that the caps of old specimens often begin to take on a greenish hue as a result of colonizing algae. The mushroom is parasitic, causing a heartwood rot, and is especially fond of sugar maple and beech; it is frequently found growing from the wounds of these trees, high above the ground.
Parasitic on hardwoods, especially green ash, sugar maple, and beech; growing in large shelf-like clusters in the wounds of living trees, or on recently dead stumps or trunks; summer and fall;