Hydnum is a genus of fungi in the family Hydnaceae. They are notable for their unusual spore-bearing structures of teeth rather than gills. The best known are the edible species Hydnum repandum and H. rufescens. The word is derived from (h)udnon/ύδνον, an Ancient Greek word for truffle. The white or buff Hydnum repandum has a spore scatterer of still another shape. The smooth cap grows as wide as 8 inches across. The stem is off-center and is less than 2 inches long. Hydnum has many brittle, white teeth from which the spores drop. The mushrooms of the Hydnum group grow both on ground and on wood. Some species have teeth which hang from ascending branches, while other species have teeth which project downwards from the undersurfaces of dead wood. Most Hydnum are safe to eat.