Earthball mushroom (Scleroderma citrinum): poisonous, and how it differs from a puffball

How to identify an earthball

Earthballs look like a small, scaly potato half-buried on a woodland path. First Nature gives 4 to 10 cm across and 3 to 6 cm tall for the common earthball; the Woodland Trust gives 4 to 12 cm; MushroomExpert.com describes North American collections at 2 to 5 cm. There is no stem, only white root-like threads anchoring the ball to the soil. The skin is tough and thick, dirty yellow to ochre-brown, broken into coarse warty scales. Cut one open and the difference from a giant puffball is immediate.

Confirm these features

• Press it: firm and hard, not soft like a marshmallow.
• Skin yellow-brown with coarse scales or warts, not smooth white.
• Cut it top to bottom: a rind 1–3 mm thick and an interior that is purple-grey to black, often marbled with white.
• No stem, no sterile base, no sac or cup under the ball.
• No neat round opening at the top; ripe ones split or crack irregularly.
• Growing on acidic, sandy or compacted soil near trees, typically on paths and banks.

Dangerous look-alikes

The earthball is the poisonous one here; the look-alikes are the fungi people mistake it for, and the fungi that could be mistaken for it.

Common puffball and giant puffball (Lycoperdon perlatum, Calvatia gigantea)

Tell apart: puffballs are soft and spongy with a skin as thin as an eggshell (UBC Beaty Museum). The common puffball is pear-shaped with a small sterile base and pearly, pointed scales; the giant puffball is a smooth white ball with no base. Cut, a young puffball is pure white and uniform all the way through. First Nature says earthballs are much less spongy than puffballs; the Woodland Trust says the earthball's flesh is never pure white. See earthball vs puffball.

Risk: the risk runs the other way. Eating an earthball you took for a puffball brings on vomiting and diarrhoea. UBC states that mistaking earthballs for truffles or puffballs has caused many poisonings.

Young Amanita eggs (Amanita phalloides, A. bisporigera, A. virosa)

Tell apart: a death cap or destroying angel egg is white and smooth, soft rather than hard, and cut lengthways shows the outline of a developing cap, stem and gills inside a white sac. An earthball cut open shows a solid dark spore mass with no mushroom shape. The puffball vs amanita page covers the cut test in full.

Risk: deadly. Amanita eggs are the most serious thing a white ball on the ground can be. The North American Mycological Association (NAMA) describes symptoms delayed 6 to 24 hours, then liver and kidney damage.

Other earthballs (Scleroderma areolatum, S. verrucosum, S. bovista)

Tell apart: the Woodland Trust notes the leopard earthball (S. areolatum) has much finer scales. All share the firm feel and the dark interior.

Risk: UBC says other Scleroderma species in its region are also poisonous. Treat every earthball the same way: do not eat.

Where and when it grows

The common earthball is mycorrhizal, living with the roots of trees. In Britain and Ireland First Nature places it on well-drained, sandy, acidic soil, compacted forest paths, shaded banks and the sides of drainage ditches, from July to early December; the Woodland Trust adds mossy and peaty ground on heaths and in woodland and calls it very common throughout the UK. In North America MushroomExpert.com finds it with oaks and other hardwoods in mixed and hemlock woods, often among moss, in summer and fall, with described collections from Indiana, Kentucky, Michigan and North Carolina. Earthballs often fruit in large numbers along the same path year after year. A small bolete, the parasitic bolete (Pseudoboletus parasiticus), grows only on common earthballs; if you see one, the ball beneath it is an earthball, not a puffball.

Symptoms and why the delay matters

Earthball toxins are unidentified gastrointestinal irritants (UBC Beaty Museum). The onset is fast compared with the deadly Amanitas, which is the one reassuring thing about it: the UBC Beaty Museum gives 10 minutes to 5 hours after eating, with abdominal pain, stomach cramps, vomiting, watery diarrhoea that can become bloody, and muscle rigidity in severe cases. Poison centres' advice is to seek urgent medical attention for any ingestion.

Children and dogs are the usual victims because they pick up and eat things from paths and lawns. Pet Poison Helpline advises treating any mushroom a pet eats as toxic until a specialist identifies it, and notes that signs can appear within 15 to 30 minutes with some toxins or take up to 24 hours with others. Call your vet or an animal poison line now rather than waiting; the dog ate a mushroom guide explains what to bring. One warning: a fast stomach upset does not rule out something worse. If any of the fungi eaten could have been an Amanita egg, the serious symptoms come later, after the first ones seem to pass.

Using an app to check a find

A photo can show an app the scaly yellow-brown skin and the setting on a woodland path, which already points away from a puffball. It cannot show firmness, rind thickness or the colour inside, so photograph the cut face as well as the outside. Mycoscout leads with the edibility verdict, shows its confidence, and names the look-alikes to rule out, including puffballs and young Amanita eggs. It is a field companion, not a clearance to eat; nothing on a screen replaces cutting the specimen open and, if you plan to eat anything, showing it to someone experienced in person.

Frequently asked questions