Slate boleteLeccinum duriusculum

The cap of the slate bolete reaches 5 to 15 centimeters across. When young it is hemispherical, becoming convex and cushion-shaped with age. The surface is smooth, dry or slightly slimy in rain, matte, often finely wrinkled in young mushrooms. The color is gray-brown, clay-brown or brownish-gray, sometimes with a pinkish tinge. The cap skin overhangs the margin slightly.

The hymenophore is tubular. The tubes are long, with small round pores, dirty white or grayish in young mushrooms, turning gray-brown with age. When pressed, the pores may slowly darken. The hymenophore separates easily from the cap flesh, as is typical of boletes. The spore print is olive-brown.

The stem is tall, dense and firm, 6 to 15 centimeters tall, whitish or grayish-white, covered along its whole length with characteristic dark — gray-brown to black — scales that form a granular, net-like pattern. At the base, the cut stem flesh often takes on a bluish-greenish tint. There is no volva and no ring. The firm, dense stem sets this species apart from the softer Leccinum species.

The flesh is white, dense and firm, especially in young mushrooms, just as the name suggests. When cut it characteristically changes color: first turning pinkish or brownish, then gray and black; at the base of the stem it may turn green. The taste is mild and pleasant, with no bitterness. Thanks to its firm texture, the mushroom holds its shape well during cooking.

The smell is faint, pleasant, typically mushroomy, with no sharp notes. The aroma is not a defining feature, so identification relies on the brown cap, the firm scaly stem, the color change of the cut flesh and the association with poplar or aspen.