Boletus edulis, the porcini, cep or king bolete, is a large ectomycorrhizal bolete found across the Northern Hemisphere with both conifers and hardwoods. It has a reddish-brown cap, pores that turn from whitish to yellow and then brown, a stout stem with a fine white net near the top, and white flesh that does not stain blue. It is one of the most widely collected wild edible mushrooms.
Choice edible and one of the safest wild mushrooms to pick; eaten cooked, dried, pickled or raw. Rule out the very bitter Tylopilus felleus (pink pores, dark net), the poisonous Rubroboletus satanas (red stem, blue bruising) and, in NE North America, Boletus huronensis (severe GI upset). It bioaccumulates mercury, cadmium, caesium and polonium, so do not collect it from polluted sites.
Never eat a wild mushroom based on a web page — confirm with an expert.
Mycology is an evolving science: names, classifications and safety information change as research advances. Entries are compiled from cited sources and reviewed, but may be incomplete or out of date — check the sources, and never rely on this library alone to identify or eat a mushroom.
Habitat
Ectomycorrhizal with pine, spruce, hemlock, fir, chestnut, chinquapin, beech, oak, Lithocarpus and Keteleeria, and with gum rockrose (Cistus ladanifer); in coniferous, broadleaf and mixed forest. Often fruits near Amanita muscaria.
Distribution
Native across the Northern Hemisphere in Eurasia and North America, from cool-temperate to subtropical zones. Introduced with exotic trees to New Zealand, Australia (Adelaide Hills), South Africa and Zimbabwe. In North America the name covers a species complex: several western porcini are now separate species (B. regineus, B. rex-veris, B. barrowsii), and B. edulis var. grandedulis is recognised in California.
Characteristics
Cap: 8-30 cm, sometimes larger; convex becoming broad; reddish brown, sometimes with a paler margin; sticky when moist. Pores: whitish when young, then yellow, then brown with age; do not stain when bruised; tubes 1-2 cm deep. Stem: 8-25 cm long, 2-7 cm thick; club-shaped to bulbous; fine white reticulation on the upper part or sometimes the whole stem. Flesh: white and firm, becoming spongy with age; no colour change or only a light brown or reddish tinge when cut. Spore print: Olive-brown. Spores: elliptical to spindle-shaped, 12-17 x 5-7 um.
