This large group of terrestrial, mycorrhizal fungi is typically recognised by the presence of a cortina, which is a veil of silky or cobwebby fibbers that protects the gills of a young mushroom. This collapses as the cap opens in most cases, leaving hairs on the stem or forming a well-defined ring that is then stained brown from spores. They are a very diverse group in shape, size, and colour. The large number of species makes this group difficult to identify.