Ruby bolete or Inkstain bolete

The cap of the inkstain bolete is small, usually 3 to 10 centimeters across. When young it is convex and hemispherical, opening with age to cushion-shaped and almost flat. The cap surface is dry and velvety-felty to the touch, and in mature mushrooms it may develop fine cracks. The color is dark and rich — from chestnut brown and chocolate to olive-brown, sometimes with yellowish tones. Its most striking trait is the instant reaction to touch: at the slightest pressure, the cap surface immediately floods with dark blue, almost black.

Cap 3-7 cm across, hemispherical in young mushrooms, later becoming convex to flat. Color bright red, raspberry-red, carmine, richer when young, fading to brownish-red with age. The surface is velvety and dry, slightly sticky in damp weather. In old mushrooms it often cracks into polygons, revealing a yellow layer under the skin (not red, as in the red cracking bolete).

Under the cap lies a tubular hymenophore with small pores that are bright yellow or golden yellow when young, turning olive-yellow as they mature. But the hymenophore's main feature is its lightning-fast and extremely vivid reaction: just touch the pores, and in an instant they flood with a deep ink-blue, almost black color. In the intensity and speed of this bluing, the inkstain bolete outdoes practically every other bolete in our forests.

The hymenophore is made of tubes attached to the stem. Color yellow when young, turning yellow-olive with age. The pores are small and stain strongly blue when pressed. Spore print olive-brown.

The stem of the inkstain bolete is thinner and slimmer than the cap, 4 to 9 centimeters tall, cylindrical or slightly tapering toward the base. It is yellowish at the top and takes on reddish-brown or rusty tones toward the base. There is no net pattern on the stem — its surface is smooth or faintly fibrous. Like the rest of the mushroom, the stem turns blue instantly and intensely when touched or pressed. There is no ring and no volva at all.

Stem 4-7 cm tall, 0.8-1.5 cm thick, cylindrical, often thickening toward the base. Color yellow at the top, with distinct reddish-brown lengthwise streaks and a delicate reddish fibrous net in the lower half. In old mushrooms the stem is redder.

The flesh of the inkstain bolete is yellowish, fairly soft and thin, especially in the stem. Its defining feature is the fastest and most vivid bluing of any bolete: as soon as the mushroom is cut, the flesh literally within seconds floods with a thick dark blue, almost inky color across the whole cut surface. This reaction is spectacular but perfectly safe. The flesh tastes mild and pleasant, with no bitterness, but because of its high arsenic content, it's best not eaten.

The flesh is thin, soft and yellow, and in the lower part of the stem with a noticeable bright yellow or yellow-orange spot when cut lengthwise — a diagnostic feature of the species. When cut, it stains strongly blue (within 30-60 sec).

The smell of the inkstain bolete is faint, mild and typically mushroomy, with no sharp or unpleasant notes. The aroma is not a defining feature of the species, so when identifying it, rely first and foremost on the dark velvety cap and the extraordinarily fast and intense bluing of every part of the mushroom.

Faint, pleasant and mushroomy, with no distinct notes.