Bay bolete

Description

The bay bolete is one of the most common boletes of Polish forests. It has a chestnut-brown, smooth cap up to 15 cm across, which is hemispherical in young specimens and then spreads out; when wet it may be slightly sticky. Underneath are tubes with pale yellow to yellow-green pores that turn blue when touched or damaged. The stem is light brown, cylindrical, with longitudinal streaks.

It grows from summer to late autumn in coniferous and mixed forests, most often under pines and spruces, often in moss and near stumps.

Young bay boletes can be confused with the bitter bolete, which has bitter flesh, and older ones with the chestnut bolete, which has a hollow stem and does not turn blue. If you are not sure of the species, do not pick or eat it.

Identification features

Cap

Diameter up to 15 cm (according to some descriptions up to 10 cm); hemispherical with an inrolled margin when young, then spread out, fairly flat. Colour dark brown with a reddish tinge or chestnut-brown. Surface bare, smooth; velvety when young, slightly sticky when wet or in old specimens; the skin is hard to peel off.

Hymenophore (underside of the cap)

Tubes slightly notched around the stem (according to some descriptions attached to notched), 0.8–1.5 cm long, from pale ochre to olive-yellow. Pores initially white to cream, later yellow to yellow-greenish, initially round, angular with age (1–2 per mm); when damaged they turn blue-green to blue-grey.

Stem

Thickness 1–4 cm, height 4–10 cm. Light brown, with longitudinal darker streaks and a fine dusting, with a fine net pattern at the apex. Swollen when young, then cylindrical, unlike the bulbous stem of many boletes. Turns blue where damaged.

Flesh

Hard, woody in older stems. White, slightly yellow in older specimens; turns slightly blue when cut (the change is often weak and transient). Taste and smell pleasant (according to some descriptions fruity). Brownish-pink under the cap skin.

Spore print and spores

Spore print brown-olive (also described as olive to olive-brown). Spores ellipsoid to slightly spindle-shaped, smooth; size 10–17 × 4–5 µm (descriptions give different ranges).

Habitat and distribution

Ecology. Terrestrial mycorrhizal fungus, with saprotrophic tendencies. Most often under Scots pine and spruce, also under beech; grows on the ground, in moss, sometimes right next to stumps. It does not occur on calcareous soils. The fruiting bodies are attacked by insects less than those of other boletes.

Distribution. North America, Europe (common), Asia (including China, Taiwan), Australia, Japan, central Mexico. Grows in coniferous and mixed forests. It is not legally protected in Poland.

Fruiting. From summer to late autumn (in the British Isles August–November).

What can it be confused with?

• Tylopilus felleus (bitter bolete) — Young bay boletes can be confused with it; the bitter bolete is bitter (do not test it by taste), has pores turning pink and a stem with a net pattern.
• Gyroporus castaneus (chestnut bolete) — Has a hollow, chambered stem, and the flesh does not change colour when cut.
• Xerocomus subtomentosus (suede bolete) — Narrower stem, paler, dry cap, wider pores that do not turn blue when pressed.
• Xerocomus bubalinus — Paler, yellow-brown cap with a pinkish-red bloom, not sticky when wet.

Never rely on a single feature. If you are not sure — do not pick it; show the mushroom to a qualified mushroom expert.

Interesting facts

• The name badia means "chestnut-brown" in Latin; the English name "bay bolete" refers to the colour of a bay horse.
• After the Chernobyl accident in 1986, specimens collected in Germany in 1986–1988 contained 8.3–13.6 times more radiocaesium than before the accident; the brown pigment norbadione A is responsible for binding caesium.
• It contains theanine, an amino acid known from green tea.
• In 2014 A. Vizzini moved it to the new genus Imleria, and in Poland the name "podgrzybek brunatny" was established in 1960 by A. Skirgiełło.