do not form a natural taxonomic group, but putting them together simplifies identification; while the toothed mushrooms range widely in their appearance, the presence of the spines helps separate them from the thousands of other mushrooms that lack spines.
Some of these mushrooms, like Auriscalpium vulgare or Hydnum repandum, are easy to identify--but others can make for a frustrating experience. I find many species of Hydnellum to be very difficult to separate (figuratively and literally, since their flesh is so tough). The key below will lead you to a species in a few instances, but is primarily designed to sort out the various genera of toothed mushrooms.