Imleria badia, the bay bolete, is an ectomycorrhizal bolete of temperate Europe, eastern North America and parts of Asia. It has a chestnut to dark brown cap that is velvety when young and slightly sticky when wet, cream to pale yellow pores that age greenish yellow and bruise blue, and a paler, faintly streaky stem with net-like ridges only at the very top. It grows mainly under conifers, less often under broadleaf trees such as beech, and sometimes on rotting stumps.
Edible and well regarded; some authors rate it close to the cep (Boletus edulis), others rank it lower. The blue staining disappears on cooking. It can cause allergic reactions in some people. It accumulates mercury, cobalt, nickel and radiocaesium, so do not collect it near pollution sources or where radioactive fallout occurred. Its look-alikes (e.g. Xerocomus subtomentosus, Aureoboletus projectellus) are not known to be dangerous, but avoid any bolete with red or orange pores.
Never eat a wild mushroom based on a web page — confirm with an expert.
Habitat
Ectomycorrhizal, mainly in coniferous woods (recorded under white pine, spruce and hemlock), less often in mixed or deciduous woods, especially with beech. Grows on the ground or on decaying stumps, often in numbers, in humid, shady places; not on chalky soils. Season: July to November in North America.
Distribution
Europe, from the British Isles east to the Black Sea region of Turkey; Asia (Jordan, mainland China, Taiwan); eastern North America from eastern Canada west to Minnesota and south to North Carolina; central Mexico. In western North America it is replaced by the similar Xerocomellus zelleri.
Characteristics
Cap: up to 15 cm, nearly spherical when young, becoming convex to flat; chestnut to dark brown; velvety when young, slightly sticky when wet or old; cuticle hard to peel from the flesh. Pores: cream to pale yellow, becoming greenish yellow to olive; about 1-2 per mm; bruising dull blue to bluish grey. Stem: 4-9 cm long, 1-2 cm thick, cylindrical, not bulbous, paler than the cap, with faint lengthwise ridges; reticulation only at the apex; white mycelium at the base. Flesh: whitish to yellowish, pinkish brown to reddish brown under the cuticle; stains faint pale blue when cut, then reverts. Odour: fruity. Spore print: olive to olive brown. Spores: smooth, 10-14 x 4-5 µm. Chemical tests: ammonia turns the cap cuticle greenish to bluish; iron(II) sulphate turns the flesh dull bluish green; KOH turns the pores golden brown. Key features: bay-brown cap, yellowish pores bruising blue, stem not netted except at the apex.
