Mottled bolete, the birch bolete with a changeable cap

Among birch boletes there’s one with an especially whimsical look: its cap seems speckled with blotches, lighter and darker swirls. It’s the mottled bolete (Leccinum variicolor), the birch bolete with a changeable cap.

It’s a bit less known than the brown birch bolete, but well worth a place in your basket. Let’s see how to recognize it by two distinctive features, where it grows and how it differs from other birch boletes.

How to recognize it

The mottled bolete gives itself away with two traits the brown birch bolete doesn’t have.

• Blotchy cap. Lighter and darker patches are scattered over a gray-brown background, like swirls or marble. Hence the name.
• Bluing flesh. When cut, especially near the base of the stem, the flesh often turns blue or green. This is normal and doesn’t signal danger.

The other features are typical of birch boletes: a spongy pore layer, a white stem with dark scales, a slender build. But it’s the blotchy cap and the bluing at the base that let you name the species with confidence.

Where it grows

The mottled bolete leans toward damper spots, though it isn’t as “swampy” as its pale sister.

Look for it:

• in damp deciduous and mixed birch woods;
• on mossy patches, along the edges of wet hollows and clearings;
• where the soil is moist but not fully waterlogged.

It often grows alongside the ghost bolete, but differs from it by its firmer flesh and blotchy rather than pale cap. Its season is just as long, from June to October.

Is it tasty?

Yes, the mottled bolete is a good edible mushroom, and even firmer than the ghost bolete. Its flesh is denser, so it holds its shape better.

It’s cooked just like the brown birch bolete: fried, boiled, pickled and dried. The bluing on the cut disappears during cooking, so it spoils neither the look nor the taste of the finished dish.

Like all birch boletes, it’s best for the table when young. Old specimens with a sagging pore layer become spongy, so it’s better not to take them.

Why the flesh turns blue and whether it’s dangerous

The bluing scares beginners, but it’s completely harmless. It’s an ordinary chemical reaction: compounds in the flesh oxidize in the air and give a blue or greenish tint.

In the mottled bolete, it’s mostly the base of the stem that turns blue, and not always vividly. It’s not a sign of poison, just a feature of the species, as natural as the darkening of other birch boletes.

The main thing is not to mistake this trait for danger. There are no poisonous birch boletes, and the only unpleasant lookalike is the bitter bolete, which stands out with its pinkish tubes and unbearable bitterness.

The weather will tell you when to go out for birch boletes. Keep an eye on moisture and warmth with our mushroom radar: it shows when conditions line up well for mushrooms to appear.

Sources

• “Identification Guide to the Fungi of Ukraine” (Kyiv, Naukova Dumka publishing house).
• Leccinum variicolor on GBIF, the global biodiversity database.
• Leccinum on MycoBank, the international fungal nomenclature database.
• Leccinum variicolor on Wikipedia.