Pavement Mushroom

Description

The pavement mushroom is a stocky, whitish agaricus with hard, compact flesh, a cap 4–10 cm (up to 15 cm) with an inrolled margin and a short, thick stem. It is easiest to recognise by the massive, double ring on the stem. The gills are initially pale pink, then dark brown to black, and the smell is pleasantly almond-like.

As the name suggests, it grows mainly in towns and cities: in parks, gardens, on roadsides, in pavement cracks, and it even pushes through asphalt. It is fairly common in Poland. The fruiting bodies are often dirty with soil and often mature below the surface.

Urban localities are a risk: the mushroom accumulates heavy metals (e.g. lead), so do not pick it near roads or in polluted places. If you have doubts about the species, especially with young, white-gilled fruiting bodies, do not pick or eat it.

Identification features

Cap

Diameter 4–10 cm, even 15 cm (according to some descriptions up to 18 cm). Hemispherical when young, flat or even with a sunken centre in older ones. The margin projects beyond the gills and stays inrolled for a long time. Surface smooth and dry, sometimes cracked into patches, whitish, does not change colour when rubbed (according to some descriptions slightly yellowing with age), often dirty with soil. Sometimes remnants of the veil on the margin.

Hymenophore (underside of the cap)

Gills crowded, narrow, free; initially pale pink, then chocolate-brown, finally blackish-brown; edges white and flocculose.

Stem

Short and thick, cylindrical or club-shaped, with a narrowed base, solid and hard; height 3–11 cm, thickness 1–4 cm. Surface smooth or woolly, whitish. Characteristic massive double ring: the upper one thick, funnel-shaped, the lower one thinner, skirt-like (hence the species name); colour from white to pale ochre. At the base a thick enveloping mycelium.

Flesh

Hard and very compact, white, does not change colour when damaged or becomes slightly pink. Smell pleasant, almond-like; taste nutty (according to some descriptions mild, typically mushroomy). Do not taste the flesh of wild specimens.

Spore print and spores

Spore print chocolate-brown. Spores elliptical, smooth, 5–7 × 4–5.5 µm.

Habitat and distribution

Ecology. Terrestrial saprotroph, growing singly or in small groups in gardens, parks, on roadsides, in thickets with elder, in pavement cracks and even in old, damaged plaster. The fruiting bodies often mature underground, pushing through asphalt and paving slabs. It often grows where road salt is used in winter.

Distribution. Europe, Asia, North America, Australia. Fairly common in Poland (8 localities were reported up to 2003), mainly in towns and cities. It is not legally protected; it appears on the list of fungi approved for sale (Ministry of Health item 42). Cultivated commercially since 1968 as an alternative to A. bisporus.

Fruiting. No data (the English name "spring agaric" suggests spring, but months are not given).

What can it be confused with?

• Agaricus bisporus (cultivated mushroom) — The wild form is darker, brownish, with a ring that can be pulled off; the pavement mushroom has a double ring. The microscope distinguishes them most reliably: four-spored basidia in A. bitorquis, two-spored in A. bisporus.
• Agaricus campestris (field mushroom) — Has only a single, fragile ring and grows in meadows, not on pavements.
• Agaricus bernardii — Often confused with it; smells of brine (a marine odour).
• Young deadly poisonous amanitas (e.g. Amanita virosa) — Amanitas have a volva at the base of the stem and white gills.

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 name bitorquis means "having two collars" in Latin and refers to the double ring formed when the veil falls away both at the top and at the bottom of the stem.
• It can push through asphalt and paving slabs, and the fruiting bodies often mature underground.
• Commercial cultivation began in 1968; it has greater resistance to viral diseases, higher temperatures and CO2 concentrations, and is less prone to bruising than A. bisporus.
• The Polish name "miejska" (urban) came about because all localities in the literature up to 2003 were in towns and cities.