Milk-white Toothed Polypore (Irpex lacteus) is widespread in Europe and North America. It is very common in the eastern United States to the Midwest, including Minnesota, but rare in the Southwest. It is exceptionally resistant to pollution toxicity. It grows on the bottom and sides of logs and fallen branches of hardwood trees.
The fruiting body is a stiff, dry, flat, spread out patch of spore surface attached directly to a branch or log. When growing on the side of a log or branch it may develop shelf-like, ⅜″ to 1½″ wide caps. The white, off-white, or cream-colored patches often fuse together creating a long row. There are 2 or 3 pores every thirty-second of an inch. The pore walls are thin and disintegrate unevenly. Eventually, only flattened, tooth-like projections less than ¼″ long remain. The flesh is thin and tough. It is not edible.