Bitter Beech Bolete

Description

The bitter beech bolete is a massive bolete with a light brown, beige or grey-olive suede-like cap up to 15 cm in diameter, yellow pores that turn blue when touched, and a thick stem that is yellow at the top and carmine-red at the bottom, covered with a delicate net. The flesh turns blue-green when cut.

It grows in summer and autumn in mountain spruce forests and deciduous forests, especially under spruces, oaks and beeches. In Poland it is fairly rare and more frequent in the south of the country, at lower mountain elevations.

It is distinguished from porcini by its red, reticulated stem and very bitter taste, but some specimens (especially old or several-day-old ones) have a faded red colour on the stem. It is inedible because of its bitterness and may cause stomach complaints. It is not suitable for the basket.

Identification features

Cap

Diameter 3–15 cm (rarely up to 20 cm). Almost spherical when young, then hemispherical, finally arched; the margin stays inrolled for a long time. Colour light brown, beige or grey-olive. Surface suede-like or finely hairy, may crack with age; the cuticle projects slightly beyond the margin.

Hymenophore (underside of the cap)

Tubes long (up to 2 cm), notched near the stem; lemon-yellow when young, later olive-yellow. Pores small (1–2 per mm), round, angular in older specimens, quickly turning blue when damaged.

Stem

Height 7–15 cm, thickness 2–5 cm; sturdy, barrel-shaped at first, then cylindrical or club-shaped. Yellow at the top, carmine-red to pinkish-red at the bottom (in old or several-day-old specimens the red may fade, replaced by ochre-brown). Covered with a net: pale under the cap, red in the middle, brown at the bottom. No ring.

Flesh

Cream to pale yellow, pinkish at the base of the stem; turns blue-green when cut. Taste intensely bitter (does not disappear after cooking); smell weak, sour, according to some descriptions sometimes strong, resembling ink. Do not taste it.

Spore print and spores

Spore print ochre-olive to olive-brown. Spores smooth, ellipsoid; size 12–19 × 4–6 µm (descriptions give different ranges); variety frustosus: 11–15 × 4–5.5 µm.

Habitat and distribution

Ecology. A mycorrhizal fungus (ectomycorrhiza), with coniferous and deciduous trees, especially spruce, beech and oak. Often grows at higher altitudes, on acidic soils, according to some descriptions also on calcareous ones.

Distribution. North America, Europe, Asia (including Japan, Korea, China, Taiwan, Turkey, Pakistan). Fairly rare in Central Europe, recently more numerous (probably because of a decline in sulphur compounds in the air). In Poland more often in the south, especially at lower mountain elevations. Not legally protected in Poland; on the 2006 Red List status R (rare).

Fruiting. In summer and autumn, from July to December.

What can it be confused with?

• Boletus edulis and Boletus reticulatus (porcini) — No red stem; the cap colour, yellow pores and red reticulation of the stem of the bitter bolete do not occur in porcini; the flesh of porcini is neither bitter nor does it turn blue so quickly.
• Suillellus luridus (lurid bolete) — Tubes orange-red, stem without red colour.
• Rubroboletus satanas (Satan's bolete) — A similarly coloured cap, but red pores.
• Caloboletus radicans (rooting bolete) — No red colour on the stem, stem tapering into a root, flesh turns blue more strongly; also inedible.
• Xerocomellus chrysenteron — Damaged fruiting bodies may be confused; stem without reticulation.

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

• It is the type species of the genus Caloboletus, created in 2014; the German name Schönfußröhrling means "bolete with a beautiful foot".
• In recent years its numbers in Central Europe have increased, probably because of a decline in the amount of sulphur compounds in the air.
• The smell of the mushroom is made up mainly of 3-octanone (47% of volatile compounds), 3-octanol and 1-octen-3-ol.
• In Poland it has been listed under the names borowik grubotrzonowy, wścieklak and goryczak.