Amanita in the context of "Ectomycorrhiza"

Edible mushrooms are the fleshy fruit bodies of numerous species of properly identified and prepared fungi. Edibility may be defined by criteria including their palatability and absence of dangerous mycotoxins. Edible mushrooms are consumed for their nutritional and culinary value, often either being cultivated or harvested wild. Easily cultivated and common wild mushrooms are often available in markets; those that are more difficult to obtain may be collected on a smaller scale.

To ensure safety, wild mushrooms must be correctly identified before their edibility can be assumed. Deadly poisonous mushrooms that are frequently confused with edible mushrooms include several species of the genus Amanita, particularly A. phalloides (the death cap). Some mushrooms that are edible for most people can cause allergic reactions in others; old or improperly stored specimens can cause food poisoning. Additionally, mushrooms can absorb chemicals from polluted locations, accumulating pollutants and potentially lethal heavy metals.

Amatoxins are a subgroup of at least nine related cyclic peptide toxins found in three genera of deadly poisonous mushrooms (Amanita, Galerina and Lepiota) and one species of the genus Pholiotina. Amatoxins are very potent, as little as half a mushroom cap can cause severe liver injury if swallowed.

Amanita muscaria, commonly known as the fly agaric or fly amanita, is a basidiomycete fungus of the genus Amanita. Its common name derives from its traditional use as an insecticide. It is a distinctive, large white-gilled mushroom typically featuring a bright red cap covered with white warts. The complex genetic diversity of A. muscaria suggests that it is a species complex. It is a widely distributed mushroom native to temperate and boreal forests of the Northern Hemisphere, now also naturalised in the Southern Hemisphere, forming symbiotic relationships with various trees and spreading invasively in some regions.

Ingestion of the mushroom can cause poisoning, especially in children and those seeking its hallucinogenic effects, due to psychoactive compounds like muscimol and the ibotenic acid; however, fatal poisonings are extremely rare. Parboiling reduces toxicity, though drying converts ibotenic acid into muscimol, retaining psychoactive effects. Some cultures use it as food after preparation. Indigenous peoples of Siberia used A. muscaria as an inebriant and entheogen. It has been controversially linked to Santa Claus, Viking berserkers, Vedic soma, and early Christianity, though evidence is sparse and disputed. Its rise in the 2020s as a legal hallucinogen alternative has led to Food and Drug Administration scrutiny.

Muscimol, also known as agarin, pantherine, or pyroibotenic acid, is a GABA_A receptor agonist with sedative and hallucinogenic effects and the principal psychoactive constituent of Amanita mushrooms such as Amanita muscaria (fly agaric) and Amanita pantherina (panther cap). It is a 3-hydroxyisoxazole alkaloid and is closely related structurally to the neurotransmitter γ-aminobutyric acid (GABA). The compound is widely used as a ligand and agonist of the GABA_A receptor in scientific research. Muscimol is typically taken orally, but may also be smoked. Peak effects occur after 1 to 3 hours orally and its duration is 4 to 8 hours but up to 24 hours.

The effects of muscimol in humans include central depression, sedation, sleep, cognitive and motor impairment, hallucinations, perceptual distortion, and muscle twitching, among others. Muscimol acts as a potent GABA_A receptor full agonist. It is also a potent GABA_A-ρ receptor partial agonist and a weak GABA reuptake inhibitor. The drug is inactive at the GABA_B receptor but is a substrate of GABA transaminase (GABA-T). Muscimol mostly exerts its effects via GABA_A receptor activation. It is very different from drugs like benzodiazepines and barbiturates as it is an orthosteric agonist of the GABA_A receptor rather than an allosteric modulator. Unlike GABA, muscimol crosses the blood–brain barrier and hence is centrally active. Muscimol, which is also known chemically as 5-aminomethylisoxazol-3-ol, is a conformationally restrained analogue of GABA. The related compound and Amanita spp. constituent ibotenic acid is a prodrug of muscimol.

Amanita phalloides (/ˌæməˈnaɪtə fəˈlɔɪdiːz/ AM-ə-NY-tə fə-LOY-deez), commonly known as the death cap, is a deadly poisonous basidiomycete fungus and mushroom, one of many in the genus Amanita. Originating in Europe but later introduced to other parts of the world since the late twentieth century, A. phalloides forms ectomycorrhizas with various broadleaved trees. In some cases, the death cap has been introduced to new regions with the cultivation of non-native species of oak, chestnut, and pine. The large fruiting bodies appear in summer and autumn; the caps are generally greenish in colour with a white stipe and gills. The cap colour is variable, including white forms, and is thus not a reliable identifier.

These toxic mushrooms resemble several edible species (most notably Caesar's mushroom and the straw mushroom) commonly consumed by humans, increasing the risk of accidental poisoning. Amatoxins, the class of toxins found in these mushrooms, are thermostable: they resist changes due to heat and cold, so their toxic effects are not reduced by cooking nor freezing.