Boletus

Boletus, a genus of fungi belonging to the class Hymenomycetes, having a thick stem and rounded mushroom-like cap or pileus, on the under surface of which numerous tubes take the place of the gills of the mushroom. The tubes are very distinct both from the cap and from one another, and are lined by the hymenium, or spore-bearing surface. There are numerous species, B. edulis (with sulphur-yellow tubes) and others, being edible, whilst B. Satanas and others, with red tubes, are poisonous. In some the flesh rapidly turns to a deep blue when broken.