Macroscopic characteristics Pileus can be nearly any shade of brown, starts convex and becomes nearly flat with maturity, and has a tackiness when it becomes wet. The cap can be between 8-30 cm. The pore surface is white when young and becomes olive-yellow with age. It does not bruise except in maturity when it may bruise olive. The pores are small and circular (2-3 per mm.) The stem is thick, usually club-shaped and can be bulbous but rarely equal. It can be 5-26 cm long, 2-8 cm thick with fine reticulations on the upper portion. The reticulations are white with pale brown. Annulus and partial veil are not present. The flesh is white and does not blue when bruised unlike some other boletes. KOH produces an orange or red reaction on the cap but has no reaction on the flesh. The spore print is olive brown.

Microscopic characteristics The spores are 13-19 × 4-7 µm, smooth elleptic and a pale yellow brown color.

The fruiting bodies can be solitary, scattered or in groups on the ground around conifers. They are found between June and October. This is an edible mushroom if keyed out correctly.

Some common names are porcini, cep, and King Bolete.

Boletus chippewaensis looks similar to B. edulis but has a pale lemon yellow cap with bright red sometimes. The pore surface is a creamy lemon yellow. Boletus nobilissimus has reticulation down the whole length of the stem.

Boletus edulis is clearly a complex of species. More work needs to be done to distinguish the species. The name Boletus edulis gets applied very generally to the choice edible species of Boletus that do not stain, have white-yellow pores, and have a reticulum on the upper part of the stipe. The actual type for B. edulis comes from Europe and is assoicated with hardwoods.

It is found throughout North America. B. edulis was origianlly classified from Europe but that particular mushroom can be distinguished from the American variety by key macroscopic characteristics.

B. edulis is mycorrhizal with conifers. The originally classified B. edulis characterized from Europe is mycorrhizal with hardwoods.

B. chippewaensis and Tylopilus felleus look similar to B. edulis.

See also Tom Volk’s page on Boletus barrowsii, Chuck Barrows’ bolete

In the western US the name B. edulis has been applied to the separate species Boletus rex-veris which fruits in the spring in the Sierra Nevada and the coastal fall variety Boletus edulis var. grandedulis.

It is edible and particularly chosen for its delicious qualities.

Tom Volk’s page on Boletus edulis: http://botit.botany.wisc.edu/toms_fungi/sept98.html