Penny bun

Description

The penny bun, or porcino, has a cap usually 6–25 cm in diameter, from whitish in young specimens, through sandy, to light and dark brown. Underneath it has tubes, not gills: white, then yellowish and olive-green. The stem is thick, barrel-shaped or club-shaped, pale, with a delicate net in the upper part. The flesh is white, firm, with a nutty taste, and usually does not change colour when cut.

It grows from May to November in coniferous, deciduous and mixed forests, most abundantly under spruces, especially in the mountains. It appears singly or in small groups, sometimes in rings.

It is most easily confused with the bitter bolete: this has tubes that turn pink, a dark raised net on the stem and a very bitter taste, and its flesh turns brown when touched. Before eating, check the tubes, the net and the colour of the flesh. Old, spongy specimens are better left in the forest.

Identification features

Cap

Diameter 6–25 cm (can reach 30 cm and more). Hemispherical when young, then convex, cushion-shaped and spreading in old ones. Colour in young specimens white, then sandy, light brown to dark brown (rarely carmine), the margin often paler. Surface matt, may be wrinkled, smooth and sticky after rain and in older specimens.

Hymenophore (underside of the cap)

Tubes 8–30 mm long, separating easily from the cap flesh, notched near the stem. Pores small, roundish (about 2–3 per mm), not changing colour when damaged. In young fruiting bodies white or cream, filled as if with cotton wool (hyphae), becoming yellowish-olive, yellow-green and olive-green with age.

Stem

Height 5–20 cm, thickness 1.5–10 cm. White, greyish-white or sandy; in young ones bulging and deeply set in the ground, later club-shaped or barrel-shaped. With a delicate whitish or light brown net, most distinct in the upper part. No ring.

Flesh

Usually white, less often cream or sandy, reddish-brown under the cap cuticle; hard in young ones, spongy in old ones. Usually does not change colour in the air (descriptions state that it sometimes browns or pinks slightly). Smell pleasant, taste mild, nutty.

Spore print and spores

Spore print olive-brown. Spores spindle-shaped to ellipsoid, smooth, 12–18 × 4.5–7 µm (descriptions give different ranges).

Habitat and distribution

Ecology. A mycorrhizal fungus with many species of trees; in Poland mainly with spruce, but also with pine, fir, beech, oak and others. Prefers middle-aged stands; in older coniferous stands it gives way to the bay bolete. Forms rhizomorphs; for the hyphae to connect with the roots, bacteria of the genus Pseudomonas are needed in the soil. Cultivation for fruiting bodies has so far not succeeded because of the close symbiosis.

Distribution. Northern Hemisphere: Europe and North America; introduced to New Zealand and southern Africa. In Poland often in the mountains, less often in the lowlands, usually rare around big cities. Not legally protected; in 1992 it was on the red list with category V, in the 2006 edition no longer. It is on the list of mushrooms approved for sale (Ministry of Health) in Poland.

Fruiting. Most often from May to November, exceptionally also in December.

What can it be confused with?

• Tylopilus felleus (bitter bolete) — The tubes turn pink with time, the flesh turns brown when touched, and the stem has a raised, dark net on a pale background. Very bitter, inedible; may cause stomach complaints.
• Boletus aereus (bronze bolete) — Almost identical, cap distinctly darker.
• Boletus reticulatus (summer cep) — Usually a cracked cap cuticle and a darker stem with a more distinct net; usually grows under oaks and beeches.
• Boletus pinophilus (pine bolete) — Cap and stem red-brown; grows under pines.
• Rubroboletus satanas (Satan's bolete) — Red stem, turns blue when damaged. Poisonous.
• Butyriboletus regius (royal bolete) — Caution: similar protected species (strict protection in Poland), not included in the Atlas. Cap pink to rose-red, tubes and pores bright yellow, stem yellow with a fine yellow net, flesh yellow. Do not pick.

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

• The species was described in 1782 by Pierre Bulliard.
• A specimen from the Isle of Skye (Scotland, 1995) weighed 3.2 kg; a fruiting body of similar size found in Poland in 2013 reached the international media.
• The Wielkopolska porcini were entered on the List of Traditional Products on 28 February 2006.
• So far it has not been possible to cultivate the penny bun for consumption because of its close symbiosis with trees.