Leccinum scabrum

{{Speciesbox

| image = birkenpilz01.jpg

| taxon = Leccinum scabrum

| authority = (Bull.) Gray (1821)

| synonyms =

Boletus scaber Bull. (1783)
Krombholzia scabra (Bull.) P.Karst. (1881)

}}

{{mycomorphbox

| name = Leccinum scabrum

| whichGills = adnate

| capShape = convex

| hymeniumType = pores

| stipeCharacter = bare

| ecologicalType = mycorrhizal

| sporePrintColor = olive

| howEdible = edible

}}

Leccinum scabrum, commonly known as the rough-stemmed bolete, scaber stalk, and birch bolete, is a species of fungus in the family Boletaceae, and was formerly classified as Boletus scaber.

The birch bolete is widespread in Europe, in the Himalayas in Asia, and elsewhere in the Northern Hemisphere, occurring only in mycorrhizal association with birch trees. This mushroom is also becoming increasingly common in Australia and New Zealand where it is likely introduced. It is an edible mushroom.

Description

File:Leccinum scabrum JPG7.jpg

The cap is {{convert|5|–|15|cm|in|round=0.5|abbr=on}} wide. At first, it is hemispherical, and later becomes flatter. The skin of the cap is tan or brownish, usually with a lighter edge;{{cite book|last1=Trudell|first1=Steve|url=https://books.google.com/books?id=WevHvt6Tr8kC|title=Mushrooms of the Pacific Northwest|last2=Ammirati|first2=Joe|publisher=Timber Press|year=2009|isbn=978-0-88192-935-5|series=Timber Press Field Guides|location=Portland, OR|pages=227–228}} it is smooth, bald, and dry to viscid.

The pores are whitish at a young age, later gray. In older specimens, the pores on the pileus can bulge out, while around the stipe they dent in strongly. The pore covering is easy to remove from the skin of the pileus.

The stipe is {{convert|5|–|15|cm|in|round=0.5|abbr=on}} long and {{convert|1–3.5|cm|in|abbr=on|frac=8}} wide, slim, with white and dark to black flakes, and tapers upward. The basic mycelium is white.

The flesh is whitish, sometimes darkening following exposure. In young specimens, the meat is relatively firm, but it very soon becomes spongy and holds water, especially in rainy weather. When cooked, the meat turns black.

The spore print is brown.{{Cite book |last=Audubon |title=Mushrooms of North America |publisher=Knopf |year=2023 |isbn=978-0-593-31998-7 |pages=347}}

= Similar species =

Several different species of Leccinum mushrooms are found in mycorrhiza with birches, and can be confused by amateurs and mycologists alike. L. variicolor has a bluish stipe. L. oxydabile has firmer, pinkish flesh and a different pileus skin structure. L. melaneum is darker in color and has yellowish hues under the skin of the pileus and stipe. L. holopus is paler and whitish in all parts.

Habitat and distribution

Leccinum scabrum is a European species that has been introduced to various areas of the world, mostly appearing in urban areas. In New Zealand, it associates solely with Betula pendula.{{cite journal |author=McNabb RFR. |title=The Boletaceae of New Zealand |journal=New Zealand Journal of Botany |year=1968 |volume=6 |issue=2 |pages=137–76 (see p. 169) |doi=10.1080/0028825X.1968.10429056|doi-access=free }} {{open access}} In North America, it can be found from June to September, except on the West Coast, where it appears from September to November.

It grows in association with birch. It has been found in association with ornamental birch trees planted outside of its native range, such as in California.{{cite web |title=Leccinum scabrum |url=http://www.mykoweb.com/CAF/species/Leccinum_scabrum.html |access-date=2009-10-18 |publisher=California Fungi}}

Uses

The birch bolete is edible but considered not to be worthwhile by some guides.{{cite book |last=Phillips |first=Roger |title=Mushrooms and Other Fungi of North America |year=2010 |publisher=Firefly Books |location=Buffalo, NY |isbn=978-1-55407-651-2 |page=276}} It can be cooked in various mushroom dishes.{{Cite book |last=Francis-Baker |first=Tiffany |title=Concise Foraging Guide |date=2021 |publisher=Bloomsbury |isbn=978-1-4729-8474-6 |series=The Wildlife Trusts |location=London |pages=178}} It can also be pickled in brine or vinegar. It is commonly harvested for food in Finland and Russia.{{cite journal|last=Ohenoja|first=Esteri |author2=Koistinen, Riitta |date=1984|title= Fruit body production of larger fungi in Finland. 2: Edible fungi in northern Finland 1976–1978|journal=Annales Botanici Fennici|volume=21|issue=4|pages=357–66|jstor=23726151}}

A few reports in North America (New England and the Rocky Mountains) after 2009 suggest that Leccinums (birch boletes) should only be consumed with much caution.{{cite web | url=http://www.fungikingdom.net/articles-by-bill-bakaitis/toxicology/diagnosis-at-a-distance.html | title=Diagnosis at a Distance |author=Bakaitis, Bill |access-date=2011-11-28}}{{cite web | url=http://leslieland.com/2009/07/wild-mushroom-warning-the-scaber-stalks-leccinum-species-may-no-longer-be-considered-safe/

| title=Wild Mushroom Warning: The Scaber Stalks (Leccinum species) May No Longer Be Considered Safe |author=Land, Leslie |access-date=2009-07-18}}

In Nordic countries all Leccinum species are considered likely poisonous unless cooked for at least 15-20 minutes.{{Cite web |title=Poisonous mushrooms in Norway |url=https://www.helsenorge.no/en/poison-information/poisonous-mushrooms/ |website=Poisons Information Centre|date=10 April 2019 }}{{Cite web |title=Tegelsopp. Leccinum versipelle |url=http://svampguiden.com/art/visa/leccinum_versipelle |website=Svampguiden}}