Hydnellum scabrosum
Hydnellum scabrosum, also called bitter tooth or bitter hedgehog, is a species of tooth fungus in the family Bankeraceae. Taxonomy. It was originally described by Swedish botanist Elias Fries as "Hydnum scabrosum" in 1836. Finnish mycologist Petter Karsten moved it to the genus "Sarcodon" in 1881. This species remained as "Sarcodon scabrosus" until 2019, when a molecular analysis using nuclear DNA showed that this and 11 other species lay genetically within the genus "Hydnellum", a genus of which harder woody flesh had previously been considered a distinguishing feature from soft-fleshed "Sarcodon". Within the genus it is most  closely related to "H. fennicum". Description. The fruit body (mushroom) has a convex to flattened brownish cap up to across that is covered with brown scales. It can be tinged with pink at the margins and darken with age. The mushroom has yellow-brown spines under the cap that are long and in diameter. They are decurrent to the stem. The pinkish brown stem is high and wide, and has a narrower base that is a characteristic greyish green colour. The flesh is whitish and has a bitter taste, rendering the mushroom inedible. The flesh smells farinaceous or like watermelon  when cut. Distribution and habitat. It is found in association with hardwood forests across Eurasia to Japan, as well as North America. Biochemistry. The species has been investigated for bioactive agents. In 2004, Tsunashi Kamo and colleagues isolated diterpenoids with experimental anti-inflammatory activity. Other diterpenoids were shown to stimulate nerve growth factor (NGF). Yet another agent, an alpha-pyrone, was shown to inhibit lettuce seedling growth. Similar species. "Sarcodon imbricatus" is similar, but the scales do not become as prominent in age. Other similar species include "S. fennicus", "S. rimosus", "S. subincarnatus", and "S. underwoodii".