Two-colored bolete or Scarletina bolete

Cap 4–15 cm, hemispherical in young mushrooms, then cushion-shaped. The color is bright red in young ones, darkening with age to brick-red or wine-red. The surface is matte, slightly sticky in wet weather, dry and faintly rough in dry weather.

The cap of the scarletina bolete is large and fleshy, reaching 5 to 20 centimeters across. When young it is neatly hemispherical, opening with maturity to convex and cushion-shaped. The cap surface is dry and velvety-felty to the touch, and may become slightly sticky in wet weather. The color ranges from warm chestnut and dark brown to yellowish brown, often with a faint reddish or olive tint. When pressed, the cap surface darkens, developing bluish spots.

The hymenophore is tubular, slightly notched at the stem. The color is bright yellow, olive-yellow in mature ones. The pores are small and angular. When pressed they slowly turn (after 1–2 minutes) dark blue or indigo — more weakly than in many bluing boletes.

Under the cap lies a tubular hymenophore with a very characteristic, warning feature — the pores here are a rich orange-red, sometimes even blood-red, while the tubes themselves stay yellow or olive-yellow. It's these red pores that make the mushroom look like poisonous species, so it calls for special care. The most important diagnostic trait is the instant, dramatic reaction to touch: just run a finger over the pores, and they immediately flood with a deep dark blue, almost inky color.

Stem 5–10 cm tall, 1–3 cm thick, cylindrical or slightly narrowing upward. Color: yellow in the upper part, red or pinkish red in the lower part. When pressed it may turn very faintly blue or not change at all.

The stem of the scarletina bolete is sturdy, dense and massive, 5 to 15 centimeters tall, often thickened toward the base. It's the stem that gave the mushroom its Ukrainian scientific and folk names: against a yellow-orange background, it is densely covered in tiny reddish and brown scale-like dots that feel like a grainy surface. Unlike its close relative the lurid bolete, the scarletina bolete has no net pattern — just this characteristic grainy "dusting". When touched, the stem turns blue just as quickly. There is no ring and no volva.

The flesh is yellowish, firm in young ones. When cut it SLOWLY (within 1–3 minutes) turns dark blue, but more weakly than in classic bluing boletes. Then it settles to a dull gray-blue.

The flesh of the scarletina bolete is thick, dense and springy, lemon yellow in a fresh cut. Its main feature is a lightning-fast reaction to air: as soon as you cut the mushroom, the flesh floods before your eyes with an intense dark blue, almost inky color, spreading from the edges to the center. This reaction is so fast and vivid that it's one of the most reliable features of the species. Near the base of the stem the flesh may have a reddish tint. Raw flesh tastes mild, with no bitterness, but you shouldn't taste it raw.

The smell is faint and neutral. The taste is mild, sometimes quite bland — without a distinct mushroom note.

The smell of the scarletina bolete is faint, pleasant and typically mushroomy, with no sharp or unpleasant notes. It carries no warning at all and may well seem appealing, so when identifying this species, rely first and foremost on the pore color and the bluing reaction, not on the aroma.