This is not blood, this is a fungus that secretes excess juice

Bleeding dental fungus looks like a creepy crime scene in the woods. This type of mushroom is called Hydnellum pekii also called “devil’s tooth fungus” or the much more pleasant-sounding “strawberries and cream.” Its characteristic sticky red liquid is a sap-like substance that oozes during a process called guttation, when the mushrooms release excess moisture from its fruiting body. However, it is not always a bright bloody shade.

To learn more about these scary-looking mushrooms (which also inspired the drug on Penguin), Popular Science turned to West Virginia University mycologist Matt Casson.

(Connected: Is this the creepiest mushroom in the forest? Yes definitely.)

Laura Baysas: Tell me a little about Hydnellum pekii.

Matt Casson: Hydnellum pekii This is a prized species of mushroom, not because of its edibility, but because of the strange jagged projections on the underside and the red blood drops that form on top of the flattened velvet cap. Although this mushroom is inedible, it is very popular among photographers and mycophiles who want to see and touch its spiny appendages and jelly-like droplets containing the pigments prized by dyers.

LB: Where can I find it?

MK: Bleeding tooth is widespread in North America and Europe, with fewer modern observations occurring in Asia and South America. Other species of Hydnellum with common names such as zone tooth, velvet tooth, orange rough-capped tooth, blue tooth, and sweet tooth are also found in North America, and depending on their stage of development and condition, they can be mistaken for bleeding tooth.

LB: What causes this sticky red liquid?

MK: The appearance of bright drops on the fungal cap is not unique to a bleeding tooth, although their size and bright red color clearly attract attention. This phenomenon of active secretion of watery droplets is commonly known as guttation and is observed in both plants and fungi. These often pigmented droplets, observed on fungal fruiting bodies and in culture, contain various solutes and bioactive molecules. A mushroom called weeping polypore (Pseudoinonotus dryadeus) that forms under oak trees here in the eastern US produces yellow to brown blobs on the cap.

(Connected: Chefs use mushrooms to turn food waste into gourmet, completely edible dishes.)

LB: I read this Hydnellum pekii contains large amounts of telephoric acid, which could one day be used to treat Alzheimer’s disease. Is there any truth to this?

MK: The blood-colored devil’s tooth drops, among other things, contain an anticoagulant called atromentine, which has similar biological activity to heparin. Telephoric acid, derived from atromentine, is of interest because of its ability to inhibit prolyl endopeptidase, an enzyme that “plays a role in amyloid precursor protein processing” in Alzheimer’s disease.

Whether this can be used for treatment is unclear and I can’t say anything coherent. However, it is not surprising that we are still discovering bioactive molecules in mushrooms that could become building blocks for revolutionary drugs and pharmaceuticals.

LB: How does his appearance change?

MK: Not every bleeding tooth you find in the woods will be “actively bleeding.” Although guttation of these fruiting bodies is common, the bright red blobs dry out and become more brown over time. The white color of the fruiting body itself darkens with bruises and with age.

As with any fungus, the likelihood of a bleeding tooth increases with the time spent searching for it. It’s true that I have yet to find one in all my years of searching. To this day, when arriving at a new camping spot, my kids ask, “What if we find a bleeding tooth, Dad?” And I answered like any dad: “Then I’ll buy everyone dessert, just not strawberries and cream!”

This interview has been condensed for clarity.