Tylopilus felleus, commonly known as the bitter bolete or bitter tylopilus, is a type of bolete characterized by slightly to distinctly pink pores on the underside of its bun-shaped brown cap, as well as a dark net on its thick stem. It is further distinguished by its intensely bitter taste. The mushroom forms mycorrhizal relationships with coniferous trees and can be found growing individually, sparsely, or in groups in coniferous woodland environments.

Cap colour ranges from grey-yellow to pale or walnut-brown, starting slightly downy and later developing a smooth, matte lustre. It begins as convex and flattens with maturity. The flesh is whitish with a pinkish tinge beneath the cap cuticle, remaining unchanged; it is thick and firm. Pores initially pale cream but later turning pinkish, the tubes are round, densely packed and fairly small, terminating in palid pores spaced between 1 and 2 per mm that turn coral pink as the fruitbody matures. Stem club-shaped, ranging from whitish to pale brown above, and paler brown to tan below. It features a pronounced network pattern in brown, forming wide meshes, particularly on the upper third. The base has a white basal mycelium. It has no ring. Spore print brownish pink.

Microscopic Features: Spores are subfusiform, measuring 11-15 x 4-5μm.

Tylopilus felleus on the www.first-nature.com web site.
Tylopilus felleus on the MushroomExpert.Com Web site.