[ Basidiomycetes > Boletales > Boletaceae > Boletus . . . ]
by Michael Kuo
Boletus edulis is a well known European bolete that grows under spruces and, depending on how the species is defined, other conifers and even 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 Boletus edulis occurs in North America is up for debate. Mushrooms meeting the general description above can be found in diverse North American ecosystems. However, molecular research has begun to reveal potential differences in ostensibly identical "Boletus edulis" collections in North America and Europe--for example, see the preliminary survey of boletes by Binder & Hibbett (2004), in which "Boletus edulis" collections line up into clearly distinct groups (type the accession numbers into the search box at GenBank if you're interested in seeing where the collections were made).
REFERENCES: Bulliard, 1780. (Fries, 1821; Saccardo, 1888; Moser, 1983; Breitenbach & Kränzlin, 1991; Hansen & Knudsen, 1992.)