Bitter Bolete Identification (Tylopilus felleus)

Check the cap, pores, and stem pattern before considering finer details.

• Cap is broad and convex to nearly flat, usually tan to brown, often 2-6 inches (5-15 cm) wide.
• Underside has pores, not gills; the pore surface is white at first, then pinkish with age.
• Stem is thick and club-shaped to nearly equal, commonly paler than the cap.
• Upper stem shows a dark brown netlike pattern that stands out against the lighter background.
• Flesh appears white in cut or broken spots and typically does not show blue bruising.

The pinkish pores and dark netted stem are especially useful field marks.

Bitter Bolete shows useful visual changes from a compact button to an expanded mushroom.

• Young plant: The cap starts rounded or cushion-like, with the margin tucked under. Pores are pale and tight, and the stalk looks thick and short.
• Mature plant: As it expands, the cap becomes broadly convex to nearly flat, often 2-6 inches (5-15 cm) across. Pores turn pinkish, and stalk reticulation stands out more clearly.
• Fruiting stage: In fully developed fruiting bodies, the pore surface is distinctly pinkish rather than white. The cap appears drier and more even, while the stout stalk stays club-shaped or enlarged below.

Bitter Bolete is most identifiable from summer into fall, when the fruiting body appears above ground. At that time, look for a brown cap, pale pores that soon turn pinkish, and a stout stalk with a dark netlike pattern. Outside the fruiting season, this mushroom is usually not visible, so there are few useful off-season identification clues.

A few boletes are regularly mistaken for Bitter Bolete.

Tylopilus felleus is widely recorded across temperate parts of North America and Europe. Geography helps only a little, since it occurs in more than one region, but habitat is useful when narrowing an identification. It is a woodland mushroom, most often found on the ground in coniferous or mixed forests, commonly with spruce, pine, or fir. Finding it in forest duff rather than grassland or wetlands supports the ID, especially in cool temperate woods.

• Serious misidentification risk: This mushroom is not known as deadly, but mushroom identification errors can be dangerous for humans and pets if the wrong species is eaten.
• Key look-alike warning: It can be confused with porcini-type boletes. A useful separating feature is the dark net-like pattern on the stalk and pinkish pores in mature Tylopilus felleus.