Leopard Earthball Identification Guide

First impression

The Leopard Earthball is small for its genus and easy to walk past. You usually meet it as a scatter of ochre-brown balls, 1.5 to 4 cm across, sitting on damp bare soil, wet clay or moss beside a woodland path. They look firm and slightly flattened, are often half embedded in the ground, and are frequently found in loose troops of half a dozen rather than singly.

Stop and look at the skin. From reading distance it appears finely speckled; under a hand lens it resolves into the pattern that gives the species its name, and that pattern is the fastest route to a confident identification.

The setting

Search damp deciduous and mixed woodland, especially along shaded path edges, mossy banks, stream sides, and heavy clay soils that hold water. It also turns up in parks, churchyards and gardens wherever suitable trees are planted.

The habitat matters because this is an ectomycorrhizal fungus: it forms root partnerships with birch, oak, beech, poplar, willow, lime and other broadleaves, exchanging soil nutrients for sugars. That means it always fruits within rooting distance of a compatible tree, and never on open grassland far from woody plants. Fruiting runs from summer through late autumn.

Step one: read the leopard skin

The ground colour of the outer surface is ochre-yellow to warm yellow-brown. Over that ground lie small, flattened, dark brown scales, and the key detail is that each scale is surrounded by a paler halo where the surface has cracked in a ring around it. Under magnification the whole surface looks areolate: a mosaic of small polygonal fields separated by pale cracks, each field carrying a darker central dot.

The effect is genuinely spotted rather than warted. Compare that in your mind with the coarse pyramidal warts of Scleroderma citrinum, which stand proud of the surface, or the fine even scurf of S. bovista, and the difference is obvious in the hand. Fresh, unweathered specimens show the pattern best; heavy rain can wash old material until it reads as plain brown, so try to assess a young one.

Step two: the rooting base

Do not pluck the ball off the top of the soil. Cut around it and lift the whole structure, because the base is a required observation.

Beneath the ball there is a distinctly narrowed, rooting, stem-like plug of sterile tissue, usually 0.5 to 2 cm long, which passes into thick white to yellowish mycelial cords running away through the soil and leaf mould. Those cords are strong and often lift a mat of soil with them. A pronounced rooting base plus visible cords is characteristic here and is one of the features that separates it from the broad-based, barely rooting S. citrinum.

Step three: cut it open

Slice a specimen vertically from top to bottom and examine the wall in cross-section. The peridium is thin for an earthball, roughly 0.5 to 1.5 mm, and firm but not massively rubbery. Cut surfaces of the wall are whitish to very pale pinkish and may dull slowly; there is no rapid vivid reddening.

The interior tells the age of the specimen and confirms the genus. The spore mass begins firm and white, passes through pale grey, then reaches the classic earthball stage: a dense purplish-black mass finely marbled with pale sterile veins, giving a marbled or veined appearance across the cut face. Later the whole interior dries into a loose powder that reads olive-brown to purple-brown.

That purple-black marbled stage is central. True puffballs never show it; they go from white directly to olive and then to brown, without the near-black veined phase.

Step four: how it opens, and reading the spores

There is no defined pore. Mature specimens tear irregularly across the top into a few coarse lobes, and the ball then behaves as a shallow open bowl from which weather gradually removes the spore dust.

You cannot take a conventional print. Instead, tip mature dust onto white paper and read the colour: purple-brown to blackish-brown. Under a microscope the definitive character appears. Spores are globose, roughly 9 to 14 micrometres including ornamentation, and covered in isolated, free-standing spines. Crucially, those spines are not joined at their tips by connecting ridges, so there is no net or reticulum. Scleroderma citrinum and S. bovista both have reticulate spores, so a single squash mount separates them cleanly from S. areolatum and S. verrucosum.

Separating it from the look-alikes

Scleroderma citrinum is much larger, commonly 4 to 10 cm, dull yellow to ochre, and covered in coarse, raised, pyramidal warts rather than flat spotted scales. Its wall is markedly thicker, roughly 2 to 5 mm, and it sits on a broad, scarcely rooting base. Its spores are reticulate.

Scleroderma verrucosum is the closest confusion. It is usually larger, with a long, stout, furrowed, stem-like base that can equal the height of the ball itself, and its scales are finer, browner and less crisply ringed, so the surface lacks the sharp leopard mosaic. Its wall is also thin. In practice, judge the base first: a short pinched root points to areolatum, a long thick furrowed pseudostem to verrucosum.

Scleroderma bovista has an almost smooth to finely scurfy surface, ochre to grey-brown, with a short base, and reticulate spores.

Scleroderma cepa is smooth or cracking into broad flat patches, has a thick wall, and its surface reddens where it is scratched.

True puffballs (Lycoperdon, Bovista) have a soft, thin, often spiny or granular skin that can be dented with a finger, an interior that goes white to olive to brown without a purple-black marbled stage, and a defined apical pore or a neat tear at the summit.

Pisolithus arhizus contains distinct pea-like chambers embedded in a black gel, which is unmistakable in section.

An immature Amanita egg is the classic trap. Cut it vertically and you will see the outline of a folded mushroom inside: cap, gills and a stem in miniature. An earthball's interior is undifferentiated at every age.

A working field sequence

1. Note the habitat and the nearest broadleaved trees.
2. Judge size: a small ball, usually under 4 cm.
3. Use a lens on the skin and look for dark dots each ringed by a pale crack.
4. Excavate the base and record whether it is a short pinched root with cords or a long furrowed stem.
5. Cut vertically and measure the wall by eye: thin, under about 1.5 mm.
6. Record the interior stage; a purple-black marbled mass confirms an earthball.
7. If you have a microscope, check that the spore spines are free and not joined into a net.