Imleria badia

Imleria badia, commonly known as the bay bolete, is an edible, pored mushroom found in Eurasia and North America, where it grows in coniferous or mixed woods on the ground or on decaying tree stumps, sometimes in prolific numbers. Both the common and scientific names refer to the bay- or chestnut-coloured cap, which is almost spherical in young specimens before broadening and flattening out to a diameter up to 15 cm (6 in). On the cap underside are small yellowish pores that turn dull blue-grey when bruised. The smooth, cylindrical stipe, measuring 4–9 cm (1+1⁄2–3+1⁄2 in) long by 1–2 cm (1⁄2–3⁄4 in) thick, is coloured like the cap, but paler. Some varieties have been described from eastern North America, differing from the main type in both macroscopic and microscopic morphology.

First described scientifically by Elias Fries in 1818, the bay bolete was reclassified as Xerocomus badius in 1931, and it is still listed thus in several sources. Modern molecular phylogenetic studies show Xerocomus to be polyphyletic (not descended from the same common ancestor), and the bay bolete is not particularly closely related to species in that genus. Often considered a poor relation of the cep (Boletus edulis), I. badia is nevertheless regarded as a choice edible mushroom by some authors, such as food expert Antonio Carluccio, and is sold in markets in Europe and central Mexico. Its mushrooms are less often infested by maggots than other boletes. Several European studies have demonstrated that the mushroom can bioaccumulate some trace metals from the soil, such as mercury, cobalt, and nickel. Additionally, the mushroom contains a pigment that concentrates radioactive caesium; specimens collected in Europe following the 1986 Chernobyl disaster contained several times more caesium-137 than those collected before the incident.