Porcini or Cornflower 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 5–15 cm, hemispherical in young mushrooms, then cushion-shaped, almost flat in old ones. Color cream, pale yellow, ochre-yellow, darkening with age to brownish yellow. Surface matte, slightly felty or finely cracked in dry weather. The cap skin does not peel. Turns blue instantly when pressed.

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.

Hymenophore tubular, white at first, then yellowish, straw-yellow in mature mushrooms. Pores small and round. When pressed they quickly turn blue, then black — one of the key diagnostic features of the species.

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 3–12 cm tall, 1–3 cm thick, cylindrical or slightly swollen at the base. Same color as the cap or a little paler. Smooth at the top, sometimes with barely visible veins lower down. In young mushrooms the stem is solid; in mature ones it has hollow chambers inside (also a diagnostic feature of the genus Gyroporus). Quickly turns blue when cut or touched.

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 or cream, brittle and fragile, chambered in the stem of mature mushrooms. Exposed to air, within 2–5 seconds it turns a vivid blue, cornflower color — the fastest reaction of any bolete. After a few minutes the blue fades to grayish blue.

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.

Smell faint, pleasantly mushroomy, with a note of fresh hazelnut. Taste mild, with no bitterness or spicy notes.