Birch bolete

Description

The birch bolete is a slender pored mushroom with a brown cap (up to several centimetres across) and a white stem covered with small, dark, rough scales. The pores under the cap are small, whitish, and grey with age. The flesh is white and usually does not change colour when cut.

It grows from summer to autumn, always under birches: in forests, but also in parks, clearings and along roads. It is common in Poland. Young, firm specimens are best; older ones have a spongy, watery cap and a woody stem.

It is recognised by the scales on the stem and by its association with birch. It can be confused with the bitter bolete, which has a network instead of scales and a bitter taste, and with other Leccinum species. If you are not sure of the species, do not pick it and do not eat it.

Identification features

Cap

Diameter 4–20 cm (descriptions give different ranges); in young specimens hemispherical to cushion-shaped, later convex, finally flattened. Cuticle bare, dry to slightly sticky; slippery and slightly slimy in wet weather. Colour from light brown (tawny) to dark brown, usually with a paler margin.

Hymenophore (underside of the cap)

Tubes up to 25 mm long, deeply notched near the stem, bulging downwards in older specimens. Colour from whitish in young ones to grey-brown in older ones. Pores almost round, small, whitish, later grey. Tubes do not change colour when damaged. The tube layer separates easily from the flesh of the cap.

Stem

Height up to 17 cm, thickness up to 3.5 cm; solid, cylindrical, slender, tapering towards the cap. White, covered with numerous dark brown to black small tufts (scales), a characteristic of the genus Leccinum. No ring.

Flesh

White to whitish-cream, may be whitish-greenish at the base of the stem. Firm in young specimens, but very quickly becomes spongy and watery, especially after rain; stem fibrous, woody in old specimens. Usually does not change colour when damaged (sometimes darkens slightly). Turns black when cooked. Taste and smell pleasant, faint.

Spore print and spores

Spore print brown to olive-brown. Spores smooth, spindle-shaped to elliptical, 13–20 × 4–6.5 µm (descriptions give different ranges).

Habitat and distribution

Ecology. Mycorrhizal fungus, associated exclusively with birches (in New Zealand with Betula pendula). Grows on the ground in deciduous and mixed forests, and also outside forests: in parks, along roadsides, near birches planted outside their natural range.

Distribution. The whole Northern Hemisphere, in Scandinavia up to 66° latitude; in the Southern Hemisphere only in Australia and New Zealand, where it was probably introduced. Common in Central Europe and in Poland. On the Polish Red List (2006) it has category V (vulnerable). Not legally protected.

Fruiting. From summer to autumn (in North America from June to September).

What can it be confused with?

• Tylopilus felleus (bitter bolete) — Inedible, bitter. The stem has no tufts but a distinct brownish network.
• Leccinellum pseudoscabrum (hazel bolete) — Grows only under hornbeams; the flesh turns from dirty pink to blackish when damaged.
• Leccinum variicolor (mottled bolete) — Grows under birches in wetter places; stem with a bluish tinge.
• Leccinum holopus (ghost bolete) — Very pale, almost white in all parts; on heathland.
• Leccinum oxydabile — Firmer, pinkening flesh and a different structure of the cap cuticle.

Never rely on a single feature. If you are not sure — do not pick it; show the mushroom to a qualified mushroom expert.

Interesting facts

• It appeared on a Polish postage stamp from the “Mushrooms of Poland” series issued on 8 May 1959 (face value 5.60 zł, print run 604,800).
• It has more than 80 scientific synonyms; the first description dates from 1783 (Bulliard).
• Outside its natural range it usually appears in cities, under planted birches (e.g. in California and New Zealand).