Brown-capped scaber stalks: the species and how to tell them apart

Brown-capped scaber stalks are several species of Leccinum: the orange birch bolete, the foxy bolete, the red-capped scaber stalk, the rare Leccinum albostipitatum and the slate bolete. Three things tell them apart: which tree the mushroom grew under, the color of the scales on the stem, and how the flesh changes when cut. Cap color tells you the least, since in all of them it varies from orange-brown to grayish brown. All are edible, but only when thoroughly cooked.

This autumn we came home from the forest with photos of brown Leccinum that we never managed to name to species. Below we're honest about why, and about what we should have checked on the spot.

Who's who among the brown-capped Leccinum

In 2005 the Dutch mycologists den Bakker and Noordeloos revised all the European Leccinum species, using DNA among other things, and their revision is still the main reference for the genus. Here, in brief, are the ones with a brown or reddish-brown cap that you can come across in Europe.

• Orange birch bolete (L. versipelle). Grows only with birch. The cap is orange or yellowish brown, and a young cap has flaps of skin hanging from the margin. The stem scales are dark, gray or blackish, even in young mushrooms. The cut flesh turns gray with a violet tinge, then black, and at the stem base it's often blue-green.
• Foxy bolete (L. vulpinum). Its partner is pine or spruce. The cap is a dark reddish brown, and the scales are gray or blackish even in young mushrooms. The flesh darkens slowly, and far less than in the birch species.
• Red-capped scaber stalk (L. aurantiacum). The only one in Europe that isn't fussy about trees: it grows with poplar and aspen, oak and birch, and less often with willow, beech or linden. The cap is red or reddish brown. The key feature: the stem scales are rusty even in young mushrooms, darkening to reddish brown with age.
• Leccinum albostipitatum (L. albostipitatum; Ukrainian pidosychnyk bilonohyi). Grows only with poplar, aspen included. The cap is bright orange, and the scales on the stem are white when young and only turn slightly brownish in old mushrooms.
• Slate bolete (L. duriusculum). Despite its Ukrainian name, which links it to birch, it doesn't grow with birch: its partners are white poplar, aspen and hybrid garden poplars, often along roads on limy clay. The cap is grayish brown or dark brown, with an even margin and no flaps. The flesh is firm, hence the Latin name.

And what about the orange oak bolete? Mycologists have argued over this one. The name was once given to red-capped scaber stalks growing under oak. But the 2005 revision found no difference between the “oak” and “aspen” mushrooms, either in structure or in DNA, so now it's simply the red-capped scaber stalk. Our catalogue still gives the oak one its own page, but for your basket it makes no difference.

Also keep in mind the common brown birch bolete: its cap is brown, so it's the one brown scaber stalks get mixed up with most often. We've already covered how to tell it from the red-capped one in brown birch bolete or red-capped scaber stalk, and the bright orange ones in orange birch bolete: how to recognise it.

Three questions worth asking a mushroom

First: which tree is nearby? Leccinum are mycorrhizal, meaning they live in partnership with tree roots, and most of them are very choosy. Birch points to the orange birch bolete or the brown birch bolete. Pine or spruce points to the foxy bolete. Poplar or aspen points to the red-capped scaber stalk, Leccinum albostipitatum or the slate bolete. But to be honest, there are almost always several trees growing near a mushroom, so use this clue together with the others, not instead of them.

Second: what do the cap margin and stem scales look like? In orange birch boletes and red-capped scaber stalks, a young cap's margin overhangs in uneven flaps of skin, up to 4–6 mm. In the slate bolete and the brown birch bolete the margin is even, with no flaps, and in the brown birch bolete it extends beyond the tubes by a millimeter at most. As for the stem scales: blackish from the start means the orange birch bolete or the foxy bolete, rusty means the red-capped scaber stalk, white means Leccinum albostipitatum. In the slate bolete they're fine, gray or blackish, and near the top of the stem they often merge into something like a net.

Third: what does the cut flesh do? This is the most important feature, and a photo of a whole mushroom won't show it. In the slate bolete the white cut flesh slowly turns violet-pink, then gray-violet-black in patches, and in places at the stem base yellow-green or blue-green. In the brown birch bolete the flesh doesn't change or just turns slightly pink; after a few hours it may go brownish or grayish, but there's never any blue at the base. In orange birch boletes and the red-capped scaber stalk the cut goes gray, violet, then black, and the stem base is often blue-green.

Our brown Leccinum: why no species name

In early October we found a pair of young Leccinum among fallen leaves, mostly birch. The caps were grayish brown, like thin felt, firm and hemispherical. The stems were pale, with fine pale scales. The cover photo shows the larger of the two close up, and you can see that the cap margin is even, with no flaps. That straight away rules out orange birch boletes and the red-capped scaber stalk, leaving two candidates: the brown birch bolete and the slate bolete.

And that's where we got stuck. We didn't look closely at a cut, so we can't say whether the flesh turned pink or black, or whether the stem base went blue. We didn't note the surrounding trees either: there were definitely birches, but we don't remember whether poplars or aspens grew nearby. Even the scales don't help. Ours are pale, almost white, and mycologists warn that in very young mushrooms, and in shade, the dark pigment on the stem may simply not have developed yet.

The same day, in another part of the forest, we photographed one more brown Leccinum, standing by a fallen birch trunk among heather, with a brown cap and a tall stem covered in gray scales. Again there's a birch nearby and not a single poplar in the frame. Going by the tree, it looks more like the common brown birch bolete than the slate bolete, but without a cut we're leaving it identified to genus only.

For the basket this uncertainty doesn't matter: both candidates are edible and are cooked the same way. But for identification it's a shame, because the slate bolete is not a common mushroom in Ukraine. In a 2012 review of Ukrainian Leccinum it has only up to fifteen finds for the whole country, while the brown birch bolete, the orange birch bolete and the red-capped scaber stalk are listed as common.

What to notice when you cut it

Here's what we now do with every unfamiliar brown Leccinum, and what we recommend you do too.

1. Before picking, look up and note which trees grow within a few meters: birch, aspen, poplar, pine, oak.
2. Look at the cap margin: do flaps of skin hang from it, or is it even?
3. Look at the scales along the whole length of the stem, especially in young mushrooms: white, rusty or blackish.
4. Cut one mushroom lengthwise, from the cap right down to the base of the stem, and photograph the cut straight away.
5. Wait a few minutes and photograph it again: in the slate bolete the pinkish-violet tinge appears slowly.
6. Check the very base of the stem separately: blue-green or yellow-green spots are an important clue.

It's a few shots instead of one, but you won't have to guess later. The best thing we did with our find was take a good photo. The worst was not cutting it.

Leccinum albostipitatum: a rare guest in our photos

Another brownish-orange Leccinum in our archive dates from early June: a young mushroom on bare ground among grass, with a rounded ochre-orange cap and a pale fringe of skin visible along the margin. The stem is white, covered in white scales with no rusty or black tinge. We identify it as Leccinum albostipitatum, but marked “probably”.

Why the caution? First, it is a rare species for Ukraine: in the 2012 review of the genus it was recorded for the country for the first time, with only 1–3 finds. Second, the 2005 revision, in which this species was described, warns that if an ordinary red-capped scaber stalk grew in dense grass, the scales on its stem can also be almost white. Then it's better to look at the cap: in the red-capped scaber stalk it is red or reddish brown, in Leccinum albostipitatum it is bright orange. Our cap is orange, but, once again, we recorded neither a cut nor the trees around.

Interestingly, both of these mushrooms long went under the same name, Leccinum aurantiacum. They were split precisely on the color of the stem scales, so white scales aren't a minor detail but the key feature. Another pale relative, with a white cap, is Leccinum percandidum, but most mycologists consider it just a pale form of the orange birch bolete.

Don't confuse it with the bitter bolete

The only truly unpleasant lookalike of brown Leccinum is the bitter bolete, also called the gall bolete. Its cap is brown too, but its pores turn pink with age, the stem has a brown net instead of scales, and the cut flesh doesn't darken. It's also very bitter, and cooking only makes the bitterness stronger. We cover how to recognise it in bitter bolete (gall bolete).

Are they edible, and how to cook them

All the European brown-capped Leccinum are considered good edibles. But raw or undercooked, they can upset your stomach. In Norway, according to the national poisons information center, an undercooked orange birch bolete is probably the most common cause of mushroom-related digestive upsets: nausea, vomiting, diarrhea and stomach pain a few hours after the meal, usually passing within a day or two. Norwegian references advise heating it for at least 15 minutes; the Swedish Svampguiden says at least 20.

More worrying reports come from North America. The voluntary poisoning registry of the North American Mycological Association includes cases of people poisoned by Leccinum eaten raw, lightly cooked and even fully cooked. Its compiler, the toxicologist Michael Beug, writes that he received six such reports in 2018–2020 and, given how severe some of the reactions were, no longer eats Leccinum himself. He has also noticed that some people become sensitized to Leccinum over time, tolerating each meal worse than the last. That said, American Leccinum are mostly different species from ours, and European references consider our species edible after proper heating.

The takeaway is simple: cook brown Leccinum for at least 15 minutes, ideally 20, don't taste them raw, and don't eat a lot at once, especially the first time. For more on cooking times, see how long to boil mushrooms. And if you get nausea, vomiting or stomach pain after a mushroom dish, follow the steps in mushroom poisoning: signs and first aid.

Flesh darkening when cut and in the pan is a normal Leccinum reaction, not a sign of a spoiled mushroom. No species of the genus Leccinum is listed in the Red Book of Ukraine.