Bovine bolete or Alder bolete

Cap 3–12 cm, hemispherical in young mushrooms, then flat-convex, almost flat when mature. The color is a dirty yellow-brown, ochre, with a pinkish tinge; in wet weather it's noticeably slimy and shiny. The skin doesn't peel, or peels only with difficulty. In dry weather the cap is matte, sometimes with small cracks at the edges.

The cap of the alder bolete reaches 4 to 10 centimeters across. When young it is convex with an inrolled margin; with age it flattens out, often with a wavy margin. The surface is smooth, sticky or slimy in wet weather and matte when dry. The color is clay-brown, yellowish ochre or light brown, darkening with age; when damaged, the surface may take on a darker tint. The flesh is thin, so the cap breaks easily.

The spore surface is made of tubes, but quite distinctive: the pores are large, angular, irregular, with thin radial walls — they look like honeycomb. The color is dirty yellow at first, greenish-olive with age, and brownish-olive in old mushrooms. The tubes are attached to the stem and often run down it.

The spore-bearing surface is made of tubes, but an unusual one: the tubes are very short, and the pores are small, angular and irregular, often elongated and interconnected, running noticeably down the stem. They are bright yellow or golden yellow, and when pressed or damaged the pores quickly turn blue, taking on a blue-green or blue-gray tint. This sudden bluing is one of the species' most distinctive features.

Stem 4–8 cm tall, 0.5–1.5 cm thick, cylindrical, often bent and curved — it's rarely straight. The color is the same as the cap or a little lighter. The surface is smooth, with no ring and no net pattern. Near the base it often has a pinkish tinge.

The stem is short and thin relative to the cap, 3 to 7 centimeters tall, often off-center or curved, and narrowing toward the base. At first it matches the cap — yellowish brown — and darkens to reddish brown with age. The surface is smooth. There is no ring and no volva. When cut, the stem flesh can also turn blue.

The flesh in the cap is yellowish and soft; in the stem it's denser and fibrous. When cut, it doesn't change color or turns slightly pink. In mature mushrooms the texture becomes rubbery, which is why some foragers only take bovine boletes when they're very young.

The flesh is soft, watery and pale yellow; when cut and exposed to air it turns blue, taking on a bluish-green tint. The taste is mild, bland and without bitterness. Because its watery texture quickly turns mushy, the mushroom has mediocre food value; only young, firm fruiting bodies are chosen for the table, and they must always be boiled.

The smell is faint, mushroomy, nothing special. The taste is mild, with no bitterness.

The smell is faint, bland and typically mushroomy, with no sharp notes. Aroma is not a defining feature, so for identification rely on the small yellow pores that turn blue, the sticky clay-colored cap and the constant link with alder in damp places.