Poison Bolete: Which Boletes Are Toxic and How to Tell

Turn it over. A bolete has a sponge under the cap instead of gills. MushroomExpert describes tubes packed so tightly that from below you only see their openings, like the surface of a sponge. Wikipedia adds that boletes are fleshy, which separates them from the tough, woody shelf fungi (polypores) that also have pores.

Boletes in yards usually grow in soil near mature trees, because they partner with tree roots (Holden Forests and Gardens). To identify one to species, MushroomExpert says you need fresh specimens, ideally young and mature, and should record the stem surface, cap surface, pore colour, any colour change when bruised or cut, the spore print, and the tree it grows under.

Wikipedia's rule of thumb is that most poisonous boletes have red pores, and it names the genus Rubroboletus, which includes Satan's bolete, as dangerously poisonous. The species worth knowing:

• Satan's bolete, Rubroboletus satanas (warm parts of Europe, with oak and sweet chestnut). Large, pale beige velvety cap, yellow to orange-red pores turning carmine, a bulbous stem that is red with a fine net, flesh that slowly turns blue when cut, and a smell that becomes like carrion with age (Wikipedia). Earlier North American records were actually the related Rubroboletus eastwoodiae.
• Red-pored bolete, Rubroboletus pulcherrimus (western North America, New Mexico and California to Washington, with Douglas-fir and tanbark oak). Olive to reddish-brown cap up to 25 cm, red pores that bruise blue or black, and a net on the upper two-thirds of the stem. In 1994 a couple ate it and the husband died; Wikipedia calls it the only bolete implicated in a death.
• Boletus huronensis (under hemlock in northeastern North America, July to October). A journal article by Bill Bakaitis for the North American Mycological Association describes a dull yellow-brown to cinnamon cap 5 to 25.5 cm across, pale yellow flesh that stains blue, and a yellowish stem without the fine net of porcini. It records several cases of exceptionally severe gastrointestinal illness and one with debilitating vertigo.
• Boletus sensibilis (east of the Rocky Mountains, with oak and beech). Pinkish-red cap 5 to 12 cm that stains blue almost instantly when handled. Wikipedia notes sources disagree on its edibility and calls it one of the less well tolerated mushrooms.
• Bitter bolete, Tylopilus felleus (eastern North America, Europe, Asia). Not poisonous but intensely bitter; white pores that turn pinkish and a dark net on the stem, the reverse of the pale net on porcini. Wikipedia says one specimen can spoil a whole dish.

The red-pore rule is a warning, not a clearance: Boletus huronensis caused serious illness without being a red-pored species in NAMA's description.

Badly, but rarely fatally. Wikipedia describes nausea, abdominal pain and violent vomiting with bloody diarrhoea that can last up to six hours, caused by a protein toxin called bolesatine, whether the mushroom is raw or cooked. Reports are rare because its colours and carrion smell put people off; claims that it becomes edible after long boiling have never been proven. No deaths are recorded in the Wikipedia article.

Wikipedia says some boletes appear to be hallucinogenic. The best documented is Lanmaoa asiatica, called jianshouqing in Yunnan, China, and sedesdem in the Philippines. Eaten raw or undercooked it causes 'Lilliputian' hallucinations of tiny people, starting 12 to 24 hours after the meal and lasting 1 to 7 days. It contains neither psilocybin nor muscimol, and the cause is still unknown. Yunnan restaurants that serve it set cooking timers and ban alcohol with it (Wikipedia). Other boletes reported as psychoactive include Butyriboletus roseoflavus, Retiboletus nigerrimus and Boletus manicus from Papua New Guinea.

Yes as species, which is exactly why people take risks with them. Wikipedia describes porcini (Boletus edulis) as a delicacy and many Suillus and Xerocomellus species as edible but not choice; Holden Forests and Gardens notes that very few boletes are toxic. None of that tells you about a particular mushroom. Boletus huronensis was reported as confused with porcini, the bitter bolete looks like young porcini, and edibility of Boletus sensibilis is disputed. This site does not say any wild bolete is safe to eat; have the actual specimen checked by an expert.

No. Wikipedia says some, but not all, boletes bruise blue, and the list above shows blue staining in both the poisonous species and ones some people eat. MushroomExpert treats the colour change as one identification feature among many, alongside pore colour, stem net and host tree. Cutting a bolete open is useful for identification; it is not a poison test.

Photograph the cap, the pore surface, the whole stem (to show any net), and a cut through the middle a minute after cutting so any colour change shows. Note the nearest tree. MushroomLens uses those features to suggest likely species and flag red-pored and other warning matches. Use the answer to know what you are looking at, not as permission to eat it. If anyone has eaten a wild bolete and feels unwell, call Poison Control at 1-800-222-1222 (US).

Research and drafting for this page were assisted by AI and checked line by line against the sources listed below. Nothing on this page says a wild mushroom is safe to eat or safe to handle. If you find an error, tell us and we will correct it.