Major Groups > Boletes > Edulis Group > Boletus edulis


Boletus edulis

[ Basidiomycetes > Boletales > Boletaceae > Boletus . . . ]

by Michael Kuo

Known as the cep in France and the Steinpilz in Germany, Boletus edulis is a well-known European bolete that associates with spruces and, depending on how the species is defined, various hardwoods. It is a large mushroom with a greasy to tacky, bald, brown cap and a meaty, swollen stem that features fine reticulation. The pore surface is initially white, with "stuffed" pores--but as the mushroom matures the pores become more visible and the pore surface becomes greenish yellow. The flesh does not change color when the mushroom is sliced, and its surfaces do not bruise on handling.

Whether or not the "true" Boletus edulis occurs in North America is up for debate. Mushrooms meeting the general description above can be found in diverse North American ecosystems (see the key below for 14 North American edulis-like species). However, recent research has revealed potential differences in ostensibly identical "Boletus edulis" collections in North America and Europe. Studies by Arora (2008), Dentinger and collaborators (2010), Nuhn and collaborators (2013), Arora & Frank (2014), and Wu and collaborators (2014) have begun to sort out the edulis-like species, but much more work needs to be done. If you have a well-documented edulis-like collection you would like to contribute to further study of this species group, please see this page.

Boletus edulis is the "type species" for the genus Boletus, which means it is the species that is supposed to represent the genus. This fact means that Boletus edulis and its close relatives will by taxonomic necessity belong to Boletus even as mycologists split the formerly large genus into a mind-numbing number of new genera.

REFERENCES: Bulliard, 1780. (Fries, 1821; Saccardo, 1888; Moser, 1983; Breitenbach & Kränzlin, 1991; Hansen & Knudsen, 1992; Knudsen & Taylor, 2008.)

This site contains no information about the edibility or toxicity of mushrooms.


Boletus edulis

Boletus edulis

Boletus edulis

Boletus edulis

Key to 15 North American edulis-like Boletes  

The key below sorts out 14 edulis-like North American boletes. In many cases, North American names have been established (at least on the basis of morphology)—but in some cases I have had to refer to European species names. Don't be surprised if your edulis-like bolete doesn't seem to fit in; this species group is in desperate need of an extensive study!

1.Found under hardwoods.

1.Found under conifers.

2.Found under live oak or other hardwoods (including madrone and tanoak) on the West Coast.

2.Found under oaks (including live oaks) and other hardwoods east of the Rocky Mountains.

3.Cap dark brown, with a whitish bloom when young; cap cuticle clearly differentiated.
Boletus regineus

3.Cap pale (nearly white), without a bloom; cap cuticle poorly differentiated.

4.Fresh cap and stem white; pore surface white when young, becoming yellow; known from the southeastern United States, the Gulf Coast, and Texas.

4.Fresh cap not white; stem and pore surface variously colored; variously distributed.

5.Mature pore surface yellow to brownish yellow, without green or olive shades; stem flushed with liver brown, at least in part; ammonia turning green on cap and stem surface.

5.Mature pore surface greenish yellow to olive yellow; stem sometimes brownish to reddish brown but not flushed with liver brown; ammonia not turning green on cap or stem.

6.Cap medium brown to yellow brown, often wrinkled when young and very finely patchy when mature; ammonia turning purple on cap surface.

6.Cap variously colored and textured; ammonia not turning purple on cap surface.

7.Cap yellow-brown; stem sometimes a little ridged but not prominently reticulate, usually about 2 or 3 times as long as the cap is wide; distributed in the Appalachian Mountains.

7.Cap variously colored; stem usually at least partially reticulate, not proportionally long; variously distributed.

8.Cap greasy to tacky, bald, cinnamon to orangish brown.

8.Cap dry, leathery or finely velvety (at least when young), variously colored.

9.Appearing in fall; cap brown to grayish brown (dark brown in variety fagicola), very finely velvety when young, often becoming finely patchy in maturity.

9.Appearing in summer; cap pale brown and leathery, sometimes becoming cracked with maturity.

10.Found in western North America.

10.Found east of the Rocky Mountains.

11.Cap pale (nearly white); cap cuticle poorly differentiated.

11.Cap more highly colored; cap cuticle clearly differentiated.

12.Found in the Rocky Mountains and the Southwest.

12.Found in the Cascade Mountains, the Sierra Nevada, or along the West Coast.

13.Found in the southern Rocky Mountains and in the Southwest; cap reddish brown to brownish red, greasy when fresh.

13.Found in the northern Rocky Mountains; cap brown, dry when fresh.
Boletus sp.
"Boletus edulis" in the sense of some western authors

14.Appearing in spring (adjusted for elevation) in the mountains of California and the Pacific Northwest; often growing gregariously or in clusters.
Boletus rex-veris

14.Appearing at other times of the year in diverse ecosystems; rarely growing in clusters.

15.Appearing in fall and winter under Bishop pine and other pines in coastal California; mature pore surface brownish to cinnamon brown.

15.Appearing in various locations and seasons; mature pore surface olive brown.

16.Cap with a whitish bloom when young, becoming bald; stem white or slightly brownish with age; appearing in montane Oregon and Washington.
Boletus regineus

16.Cap velvety to finely hairy; stem brownish; appearing in various California and Pacific Northwest ecosystems.
Boletus fibrillosus

17.Appearing under loblolly pine and other pines along the Gulf Coast; cap dry, reddish to reddish brown; stem brownish to reddish brown, not usually swollen.
"Boletus pinophilus"
in the sense of southern authors

17.Appearing under spruces and pines in northeastern North America, perhaps as far south as North Carolina; cap greasy to tacky, orangish brown to cinnamon; stem white (perhaps faintly brownish with age or handling), usually swollen, at least when young.

References used for this key can be found in the reference list for boletes.

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Kuo, M. (2016, September). Boletus edulis. Retrieved from the MushroomExpert.Com Web site: