The bitter bolete, scientifically known as Tylopilus felleus, is not poisonous but has been known to ruin a feast due to its bitter taste. This is mainly because of its striking resemblance to the much sought-after and beloved king bolete, aka porcini, aka cep. Mistakenly foraging the bitter bolete is common and not a pleasant surprise for the taste buds.
All About The Bitter Bolete
The bitter bolete is known by various names, reflecting its characteristics and unpleasant taste. The species name “felleus” comes from the Latin “fel,” meaning “bile,” a nod to its bitter taste. Among the common names, bitter bolete is the most prevalent. In the United States, it’s also known as the “bitter tylopilus.” Or “The Great Betrayer,” a nod to its ability to raise the hopes of any forager who stumbles across it, only to be bitterly (sic!) disappointed upon realizing this massive, delectable-looking mushroom is not going to the dining table.
This impressive mushroom can be found in various regions across the globe, including East Asia, Europe, and Eastern North America. Its distribution extends from Mexico and Central America to the northern reaches of the continent.
In the late 18th century, the bitter bolete was described by the French mycologist Jean Baptiste François Pierre Bulliard. Bulliard initially classified it as Boletus felleus. However, nearly a century later, in 1881, Finnish mycologist Petter Adolf Karsten moved it to the new genus Tylopilus. The mushroom holds the honor of being the type species of the Tylopilus genus and is the only member of the genus found in Europe.
Bitter Bolete Identification Guide
The fruiting season typically spans from late summer to fall.
The bitter bolete is a mycorrhizal fungus, meaning it forms a symbiotic relationship with trees. It’s commonly found under conifers but may also appear in mixed or hardwood forests. It prefers well-drained, acid soils and is found growing alone, scattered, or gregariously.
This mushroom has a wide distribution, with a presence extending from the eastern regions of North America to various parts of Europe and Asia. In North America, this mushroom is commonly encountered east of the Rocky Mountains.
The bitter bolete’s cap starts as a dome in the younger stages, sporting a light brown or tan color, sometimes with an olive tinge. As the mushroom matures, the cap darkens to a deeper shade of brown and spreads out. The cap is smooth and, with maturity, often develops wavy edges. It can be quite large, measuring up to 12 inches in diameter. More often, it is around 6-8″ across. Over the course of its life, the cap exhibits various shades of brown, buff, or tan.
The pores of this mushroom are initially pale cream but turn pinkish as the mushroom grows older. When handled or bruised, the pores gradually turn brown.
The stem of this bolete measures between 1.5 and 7 inches long. It is club-shaped or thicker towards the base. The top of the stem is whitish to pale brown, while the lower portion is tan. A coarse, brown, net-like pattern (reticulation) appears at the top of the stem, sometimes spreading down the stem quite a ways.
The flesh of the bitter bolete is thick, soft, and white. As the mushroom ages, the flesh turns spongy. It doesn’t change color when cut.
Odor and Taste
What sets this bolete apart is its taste. It’s incredibly bitter, a feature that’s intensified when cooked. Its odor, however, is not distinctive or slightly mushroomy.
The spore print of the this mushroom is a brownish-pink color.
Bitter Bolete Similar Species
King Bolete/Porcini/Cep/Penny Bun Bolete (Boletus edulis)
Both the bitter bolete and king bolete share a brown cap, large size, and reticulated stem. However, the pore surface of the king bolete does not turn coral pink like those of its bitter lookalike. If ever in doubt, a quick nibble and spit taste test will tell you if you’ve found the bitter bolete instead of the king bolete.
This species closely resembles the bitter bolete but can be distinguished by its dark purple-brown to blackish cap and dark reddish-brown spore print. It also has a distinct beveled (sloping) edge. This is an edible species, so if you’re lucky, you’ve found this instead of the bitter one!
Another lookalike, Tylopilus indecisus, has a similar appearance to the bitter bolete but lacks the distinctive pink pore surface. It also has a stem that is equal in width, not club-shaped like the its bitter cousin. Finally, there may or may not be reticulation at the top of the stem. If there is, it is not as distinctive or very fine.
Bitter Bolete Edibility
Despite its intriguing appearance, the bitter bolete is not considered edible due to its extremely bitter taste. Even a single specimen used in a meal can render it inedible. However, in some cultures, this mushroom is dried and used as a substitute for pepper.
Bitter Bolete Medicinal Properties
While the bitter bolete may not be edible, it might have medicinal purposes. Compounds from this mushroom have been tested for potential medical uses. A compound named Tylopilan, a beta-glucan that has been isolated from the fruit bodies, has shown cytotoxic properties and is known to stimulate a non-specific immunological response.
Bitter Bolete Common Questions
Are bitter boletes poisonous?
No. These mushrooms are not poisonous but they aren’t any fun to eat, either. They won’t make you sick, just greatly offend your taste buds!