What is a Xerocomus bolete, and how do you recognize one?

Among mushrooms there's a whole crew of modest but pleasant hard workers, grouped under one gentle word: “moss bolete.” The name says it all: these mushrooms love moss, mossy forest edges and green clearings, where they hide from prying eyes.

The moss bolete isn't as showy as porcini or as famous as the slippery jack, but it has earned its place in the basket. Let's look at what it is, how to recognize it, where to find it and why it turns blue so dramatically when cut.

What is a moss bolete

“Moss bolete” isn't one mushroom but a whole group of related pored mushrooms from the genera Xerocomus, Xerocomellus and their close relatives. They're all relatives of porcini, just more modest and smaller.

Our best-known species are the suede bolete, red cracking bolete and ruby bolete. They're all edible, grow in similar places and share recognizable features.

What unites them is a love of moss, a velvety cap and a tube layer underneath instead of gills. They're typical “middle-of-the-road forest mushrooms,” and easy to learn to recognize.

What a moss bolete looks like

Moss boletes have a few characteristic features that make them fairly easy to tell apart.

• Cap from olive-green and yellow-brown to chestnut, dry, velvety to the touch; in some species it cracks over time.
• Tube layer under the cap, yellow or greenish yellow, with large angular pores.
• Stem thinner and more even than in porcini, with no net pattern, sometimes with a reddish tinge.
• Flesh yellowish or whitish; when cut, it often turns blue.

A dry, velvety cap, yellow angular pores and blue bruising when cut are the most reliable set of moss bolete features.

Why moss boletes turn blue when cut

The blue bruising scares beginners, but it's completely harmless and even helps you identify the mushroom.

When you cut or break a moss bolete, its flesh quickly turns blue or green in the air. It's an ordinary chemical reaction: substances in the flesh are oxidized by oxygen. It has nothing to do with poison.

Most edible moss boletes turn blue to some degree, so this sign on its own is no reason to throw a mushroom away. The blue disappears during cooking, and the dish comes out its usual color.

Where and when moss boletes grow

The moss bolete loves bright, not-too-damp forests and, of course, moss.

It's worth looking for:

• in mixed forests, where conifers grow alongside broadleaf trees;
• in coniferous forests and pine forests on mossy patches;
• in deciduous forests, on forest edges, in clearings and along paths;
• on mossy slopes, hummocks and old stumps nearby.

The moss bolete season is long, from June to October. It fruits most abundantly in the second half of summer and early autumn, especially after warm rains.

Is it worth picking

The moss bolete is a good edible mushroom, though less firm than porcini. Young moss boletes are fragrant and pleasant; they're fried, boiled, pickled and dried.

There's one catch: moss bolete flesh is softer and more watery than porcini's, so the mushroom quickly turns spongy with age. For the table, pick mainly young, firm specimens.

Moss boletes have no poisonous lookalikes, but there is one unpleasant relative, the peppery bolete, fiery to the taste. You can recognize it by its reddish pores and sharp, peppery aftertaste. To head into the forest just when moss boletes are coming up, go by our mushroom radar: it shows when moisture and warmth line up well for mushrooms to appear.

Sources

• “Field Guide to the Fungi of Ukraine” (Kyiv, Naukova Dumka Publishing).
• Xerocomus subtomentosus on GBIF, a global biodiversity database.
• Xerocomus on MycoBank, an international fungal nomenclature database.
• Xerocomus subtomentosus on Wikipedia.