Leccinum scabrum

Description

Leccinum scabrum is a medium to large bolete that has a brown cap with gray-white pores and a white to gray stem covered with gray-black scales. It grows specifically with birch, often on damp ground.

This common edible Autumn mushroom is not as firm and tasty as the best boletes, but mixed with other mushrooms it’s not bad.

In California, it appears to be restricted to ornamental birches (Betula spp.) planted in urban areas, and presumably was introduced on nursery rootstock. It often fruits with another birch-loving species, Lactarius pubescens var. betulae.

The flesh of young specimens, which is whitish, usually does not change much, although sometimes it can become somewhat brownish after exposure. The taste is mild, but the flesh is often soft and marshmallow.

Common names: Brown Birch Bolete, Birch Scaber Stalk, Common Scaber-Stalk.

Mushroom Identification

1. Pileus

   Cap 5.0-14.0 cm broad, convex, broadly convex in age with a decurved margin; surface when young, dingy-tan, dull, matted-tomentose, subviscid, occasionally areolate; at maturity sometimes weathering glabrous, becoming viscid, medium-brown to dull olive-brown; context soft, up to 1.5 cm thick, cream-colored, unchanging or occasionally faintly pink or blue were cut or injured; odor and taste mild.

2. Hymenophore

   Pores cream-buff to pale tan, bruising pale olive-buff, deeply depressed at the stipe; tubes 1-2 cm long, pallid when young, in age pale coco-brown, unchanging when cut or bruised.

3. Stipe

   Stipe 8.0-14.0 cm long, 2.0-4.0 cm thick, clavate in youth, becoming subclavate to equal at maturity, solid, straight; surface of apex pruinose, pallid to cream, longitudinally ridged below, sometimes forming a coarse reticulum, ornamented with black squamules; partial veil absent.

4. Spores

   Spores 14-18 x 5-6 µm, subfusoid to narrowly ellipsoid, smooth, thin-walled with variously-sized vacuolar inclusions; spore print dull brown.

5. Habitat

   Solitary to scattered under ornamental birch (Betula spp.). fruiting in late summer in watered areas, again shortly after the fall rains.

Leccinum scabrum Similar Species

1. Leccinum cyaneobasileucum

   Found under birches, has flesh that turns blue near the stem base.

2. Leccinum versipelle

   Has a more orange cap and bruises blue-green in the stem base.

History

The Brown Birch Bolete was described in 1783 by French naturalist Jean Baptiste Francois (Pierre) Bulliard, who gave it the binomial scientific name Boletus scaber. The currently-accepted scientific name Leccinum scabrum dates from an 1821 publication by British mycologist Samuel Frederick Gray (1766 - 1828).

Synonyms of Leccinum scabrum include Boletus scaber Bull., Krombholziella scabra (Bull.) Maire, Leccinum roseofractum Watling, Boletus avellaneus J. Blum, Leccinum subcinnamomeum Pilát & Dermek, Leccinum avellaneum (J. Blum) Bon, Krombholziella roseofracta (Watling) Šutara, Leccinum rigidipes P.D. Orton, Leccinum onychinum Watling, Leccinum umbrinoides, Leccinum molle, Leccinum oxydabile, and Leccinum pulchrum.

Leccinum, the generic name, comes from an old Italian word meaning fungus. The specific epithet scabrum means with scabers - a reference to the rough or scurfy surface of stems of this species.

Photo sources:

Photo 1 - Author: Holger Krisp (CC BY 3.0)

Photo 2 - Author: Viktoria Bilous (CC BY-SA 4.0)

Photo 3 - Author: Holger Krisp (CC BY-SA 4.0)

Photo 4 - Author: mangoblatt (Public Domain)