How to tell Porcini from Devil's 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 8–30 cm across, massive, globular in young mushrooms, then cushion-shaped. Surface dry, matte, pale gray or grayish ocher, with no bright coloring — it contrasts with the red pores. In old mushrooms the cap is often blotchy.

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.

Pored hymenophore. Pores bright red or blood-red — the mushroom's most noticeable feature. When pressed they turn blue very intensely and quickly. Tubes yellow or yellow-green near the stem.

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 5–15 cm tall, 4–10 cm thick, massive, globular or barrel-shaped. Covered with a characteristic bright red net pattern on a yellow background — especially in the upper part. Turns blue when pressed.

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 yellowish, very firm, heavy. Turns blue in a flash when cut — the reaction comes within 3–5 seconds and is far more intense than in edible bluing species. In old mushrooms the flesh has an unpleasant smell.

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.

In young mushrooms the smell is unobtrusive or absent. In mature mushrooms it is rather unpleasant, rotten or ammonia-like, especially noticeable in hot weather. The smell gets stronger when dried.