Blue mushrooms are captivating, but their striking coloration often raises questions about their edibility and potential toxicity. While not all are poisonous, many require extreme caution in the wild. Color alone is not a reliable indicator of safety.
Understanding Blue Coloration in Mushrooms
The blue coloration in mushrooms, especially when bruised or cut, is a result of a chemical reaction involving oxidation. In species containing psilocybin and psilocin, like Psilocybe, injury exposes these compounds to oxygen, triggering an enzymatic cascade. Enzymes convert psilocybin to psilocin, which then oxidizes and polymerizes into blue compounds, causing the distinct stain. This bluing reaction is a chemical defense mechanism, potentially deterring insects from consuming the mushroom.
Not all blue staining is due to psilocybin. For instance, the edible Gyroporus cyanescens turns blue upon bruising due to the enzymatic oxidation of a chemical called gyrocyanin, which is distinct from psilocybin. This highlights that while bluing often signals the presence of psychoactive compounds, it can also occur in mushrooms without such properties due to different chemical processes.
Identifying Common Blue Mushrooms
Identifying blue or blue-staining mushrooms requires careful attention to characteristics beyond just color, given the varied nature of their bluing reactions and edibility. Some blue-staining boletes, such as Gyroporus cyanescens, are considered edible, despite their rapid and intense blueing when cut or bruised. Its yellowish to buff cap can reach up to 12 cm in diameter, and its thick stem turns an intense blue color within moments of bruising. Cooked Gyroporus cyanescens has a mild, nutty flavor and a meaty texture, and its blue color largely disappears with sautéing.
Conversely, many blue-staining mushrooms are psychoactive, due to psilocybin and psilocin. Species like Psilocybe cyanescens (wavy caps) and Psilocybe cubensis are known for blue-staining when handled. Their caps are typically caramel to chestnut-brown when moist and often have wavy margins, with the entire mushroom bruising blue or blue-green. These mushrooms are not deadly, but they cause significant psychoactive effects, including altered perception and hallucinations, making accidental consumption dangerous.
Highly toxic or deadly mushrooms exist, though prominent bluing is less common among them. For example, some Cortinarius species can have blueish tints, and while Entoloma hochstetteri is inherently blue, it is found in specific regions like New Zealand and is considered toxic. While a common caution for boletes is to avoid those with red pore surfaces that bruise blue, this is not a universal rule. The presence of red pores and blue bruising in some boletes, like those in the genus Rubroboletus, does not inherently indicate toxicity, as these reactions are due to different chemical compounds than those in psychoactive mushrooms.
Recognizing Mushroom Poisoning Symptoms and Seeking Help
Mushroom poisoning symptoms vary widely by mushroom type and toxin, but common initial signs often include gastrointestinal distress. Nausea, vomiting, abdominal pain, and diarrhea often appear anywhere from 20 minutes to several hours after ingestion. More severe symptoms can include neurological effects like hallucinations, seizures, and altered consciousness, or even organ damage, like liver or kidney failure. Symptoms that appear quickly (within two hours) are generally less dangerous than those that manifest later (after six hours), which can indicate more severe poisoning.
If mushroom poisoning is suspected, immediate action is crucial. Contact emergency services or a poison control center without delay, even if symptoms have not yet appeared. The Poison Control Center in the United States can be reached at 1-800-222-1222. If possible, saving a mushroom sample or photograph can greatly assist medical professionals and mycologists in identifying the species and determining the appropriate treatment. Do not attempt to induce vomiting unless specifically advised by medical personnel.
Safe Foraging Practices
Approaching wild mushrooms with caution is essential, as many toxic species resemble edible ones. A fundamental principle in mushroom foraging is “when in doubt, throw it out” – if identification is not 100% certain, do not consume it. Relying solely on visual characteristics like color, smell, or bluing is insufficient for accurate identification.
Learning from experienced foragers and using multiple reliable field guides specific to your region are important steps for safe foraging. Cook all wild mushrooms thoroughly; cooking can destroy some natural toxins and improve digestibility, though it will not make poisonous mushrooms safe. Avoid collecting mushrooms from contaminated areas, like roadsides or pesticide-treated lawns, as mushrooms can absorb chemicals from their environment.