Common Earthball

Description

The common earthball is a spherical or tuberous mushroom with no stem, up to 10 cm across, with a thick, hard, straw- to ochre-yellow skin covered with flat warts. The interior is at first whitish, very quickly turns yellowish-greenish, and finally black with a violet tint; the ripe fruiting body splits and releases brown spores.

It grows from June to November on the ground, on sands and acidic soils, at forest edges, in parks, on pastures and in scrub. In Poland it is common.

It is sometimes confused with young puffballs, which are uniformly white and soft inside. When the fruiting body is cut, the earthball has a hard interior that darkens very quickly. In the past young fruiting bodies were sometimes used as a seasoning, but this is a poisonous species. If you are not certain of the species, do not collect or eat it.

Identification features

Cap

No cap: the fruiting body is stalkless, irregularly spherical or tuberous, up to 10 cm across (height up to about 6 cm), hard and heavy, with a thick peridium. Peridium straw-yellow, ochre-yellow to yellow-brown-ochre, covered with flat warts 1.5–4 mm high and wrinkled with furrows converging at the base; only the base is smooth. Attached to the substrate by cords of mycelium.

Hymenophore (underside of the cap)

No gills or tubes: the spore-bearing layer (gleba) is inside the peridium. In young fruiting bodies white, soon yellowish-greenish, finally black with a violet tint, divided by thin white fibres. When ripe the fruiting body splits irregularly and releases the spores (without a single opening at the top).

Stem

No stem; at the base a smooth part from which a cord of mycelium grows.

Flesh

Interior hard, compact; the gleba darkens quickly (already at an early stage of development), unlike puffballs, which stay white inside for a long time. Smell strong, spicy, some describe it as unpleasant. Taste described as reminiscent of truffles — it must not be tasted; do not taste the flesh of this or any suspicious mushroom.

Spore print and spores

Spores spherical, brown, with a net-like ornamentation, diameter 8–13 µm. Ripe gleba black-violet.

Habitat and distribution

Ecology. Mycorrhizal fungus (ectomycorrhiza with trees). Grows on the ground, on sands and acidic soils, at forest edges, in parks, on pastures, peat bogs, stony ground and in scrub. Sometimes parasitised by Pseudoboletus parasiticus.

Distribution. Widespread in North America, Europe and Asia; rarer in South America, North Africa and Australia. Common in Poland. Not legally protected in Poland.

Fruiting. From June to November.

What can it be confused with?

• Lycoperdon perlatum (common puffball) and Apioperdon pyriforme (stump puffball) — Puffballs have a soft interior, white for a long time, and a single opening at the top through which the spores escape; the earthball has much firmer flesh, a thick peridium and a dark gleba much earlier, and splits irregularly, without a single opening.
• Calvatia gigantea (giant puffball) — Sometimes confused; the giant puffball is much larger and has a soft, white interior. Detailed differences: no data.
• Scleroderma bovista (potato earthball) — Has a distinct, well-developed mycelium at the base resembling a short root.
• Truffles (Tuber) — Inexperienced collectors confuse truffles with it; detailed differences: no data.

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 is sometimes called the "false truffle", because inexperienced collectors confuse it with truffles.
• It is sometimes parasitised by the fungus Pseudoboletus parasiticus.
• It was described in 1801 by Christiaan Hendrik Persoon; formerly it was placed among the Gasteromycetes.
• In Britain it is the most common species of earthball.