Porcini or Chestnut bolete

Cap 7–30 cm across, spherical or hemispherical in young mushrooms, becoming cushion-shaped and spread out over time. The color varies from light brown to dark chestnut or reddish brown depending on light and forest type: caps are darker in spruce woods and lighter in pine forests.

The cap surface is dry, smooth or slightly wrinkled, and can be a little sticky in wet weather. The margin is even or slightly wavy, inrolled in young mushrooms. The skin doesn't peel.

Cap 3–12 cm, hemispherical in young mushrooms, then flat-convex or flat. Color chestnut-brown, reddish-brown, sometimes lighter — hazel. The surface is dry, finely felty to the touch, and may crack slightly in old mushrooms. The skin does not peel off.

The hymenophore is tubular and separates easily from the cap flesh. In young mushrooms the tubes are white, later turning yellow; in mature ones they're yellow-green or olive. The pores are small, round, uniform in color and don't change color when pressed.

Pore surface of tubes, white at first, then yellowish to straw-colored. Pores small and round. They do NOT turn blue when pressed — this is the key difference from its relative Gyroporus cyanescens.

Stem massive, 5–20 cm tall and 3–10 cm thick, bulbous or club-shaped in young mushrooms, later cylindrical. Color from whitish to light brown. The surface is covered with a characteristic white or cream net pattern, most distinct in the upper part of the stem.

There's no ring and no volva. The base of the stem is often thickened.

Stem 4–8 cm tall, 1–3 cm thick, cylindrical or slightly tapering toward the base. Same color as the cap or a little lighter. The surface is finely felty. The most distinctive feature: in mature mushrooms the stem is hollow inside, with uneven chambers — like dried bamboo.

The flesh is dense, juicy and white, and doesn't change color when cut or damaged — this feature sets porcini apart from a number of poisonous lookalikes. In old fruiting bodies the flesh becomes spongy and yellowish.

The taste is mild, nutty and slightly sweet. The stem flesh is denser and more fibrous than the cap flesh.

Flesh white, brittle, does NOT change color when cut (an important feature — other boletes with a chestnut cap often turn blue or pink). Hollow in the stem of mature mushrooms.

The smell is pleasant, unobtrusive, mushroomy with light nutty notes. With cooking and drying the aroma intensifies and takes on a deep, rich woody, foresty character. It's for dried porcini that the mushroom is so valued in cooking — no other dried mushroom gives such a pronounced taste and smell.

The smell is faint, pleasantly mushroomy with a hint of nut. The taste is mild, sweetish, reminiscent of a real chestnut.