Bleeding tooth fungus looks like a ghoulish forest crime scene. This type of mushroom called Hydnellum peckii also goes by “devil’s tooth fungus” or the much more pleasant sounding “strawberries and cream.” Its signature gooey red liquid is a sap-like substance that oozes out during a process called guttation when the fungi releases excess moisture from its fruiting body. However, it is not always this bright blood-colored hue.  To learn more about these grisly looking fungi (that was also an inspiration for the drug on The Penguin), Popular Science reached out to West Virginia University mycologist Matt Kasson.  [Related: Is this the creepiest fungus in the forest? Yes, definitely.] Laura Baisas: Tell me a bit about Hydnellum peckii. Matt Kasson: Hydnellum peckii is a prized mushroom species not for its edibility, but its strange tooth-like projections on the underside and red blood-like droplets that form atop a flattened velvet-like cap. Though inedible, it’s a highly sought-after fungus by photographers and mycophiles alike who want to see and touch its spiny projections and jelly-like droplets which contain pigments coveted by dyers.  LB: Where is it found? MK: Bleeding tooth can be found widely distributed across North America and Europe with fewer contemporary observations in Asia and South America. Other Hydnellum species with common names like zoned tooth, velvet tooth, orange rough-cap tooth, blue tooth, and sweetgrass tooth also occur in North America and depending on their developmental stage and condition might be mistaken for bleeding tooth. A pure culture of the blushing rosette fungus (Abortiporus biennis) growing in Dr. Matt Kasson’s lab at West Virginia University. Similar to bleeding tooth fungus, the blushing rosette produces blood-colored exudates both in culture and on fruiting bodies in nature. Blushing rosette was grown out from a fruiting body found underneath a declining oak tree in WVU’s Core Arboretum. CREDIT: Matt Kasson LB: What causes this gooey, red liquid? MK: The appearance of brightly-colored droplets atop the fungal cap is not unique to bleeding tooth, though their size and bright red color are clearly eye-catching. This phenomenon of active exudation of watery droplets is commonly known as guttation and is seen in both plants and fungi. These often pigmented droplets seen on fungal fruiting bodies and in culture contain various dissolved substances and bioactive molecules. A fungus called the weeping polypore (Pseudoinonotus dryadeus), which forms underneath oak trees here in the eastern U.S., produces yellow to brown droplets atop the cap.  [Related: Chefs are using fungus to transform food garbage into fancy, fully edible dishes.] LB: I’ve read that Hydnellum peckii is high in thelephoric acid that could one day be used to treat Alzheimer’s disease. Is there any truth to this? MK: The blood-colored droplets of the devil’s tooth contain among other things an anticoagulant called atromentin, which has been described as having similar bioactivity to Heparin. Thelephoric acid, which is derived from atromentin, is of interest due to its ability to inhibit prolyl endopeptidase, an enzyme that “has a role in processing amyloid precursor protein” in Alzheimer’s disease.  Whether this can be used for treatment is unclear or outside my expertise to say anything resembling coherent. However, it’s not surprising that we are still discovering bioactive molecules in fungi that may provide the building blocks for breakthrough drugs and pharmaceuticals.  A young fruiting body of the weeping polypore (Pseudoinonotus dryadeus) at the base of an oak tree in Morgantown, West Virginia with characteristic yellow to brown pigmented droplets or exudates, a phenomenon we call guttation. CREDIT: Matt Kasson LB: How does its appearance change? MK: Not every bleeding tooth you find in the forest will be “actively bleeding.” Though guttation is a common occurrence on these fruiting bodies, the bright red droplets eventually dry up and turn more brown colored. The white color of the fruiting body itself darkens upon bruising and with age.  Like any other fungus, encountering a bleeding tooth increases with time spent looking for it. It’s true I haven’t found one yet in all my years of searching. To this day, my kids will ask upon arriving at a new hiking location, “What if we find a bleeding tooth, dad?” And I responded like any dad would, “Then I’ll buy everyone dessert, just not strawberries and cream!” This interview has been condensed for clarity. The post That’s not blood, it’s a fungus oozing excess juice appeared first on Popular Science.