How to tell Cornflower bolete from Devil's bolete

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.

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.

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.

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 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.

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.

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.

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.

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

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.