Scaly Earthball Identification Guide

The first impression

You tend to find this one on light, sandy ground rather than deep leaf mould: the edge of a sandy path, a thin grassy bank under oak or birch, a park lawn where the soil is free-draining, a disturbed roadside among poplar or lime. What you see is a firm, dull ochre to tan ball, usually 2 to 6 cm across, sitting rather high on the ground with a visible neck beneath it. That neck matters. Many earthballs squat flat on the soil like a potato; this one is typically raised on an obvious stalk-like base, which is the first character to note before you touch anything.

The surface is not smooth. Under low light you can see the ground colour broken up by small, darker brown, appressed scale-like patches, and it is those that give the species its name. Run a thumb across the top: they rub away readily, leaving a paler, slightly mottled skin behind. Handled specimens in a basket therefore look much smoother than they did on the ground, which is a common source of confusion.

Reading the outer wall

Cut the ball cleanly in half from top to bottom. The first measurement to take is the thickness of the outer wall, the peridium. Here it is thin, usually well under 1.5 mm, and it slices easily, almost like thick paper or a piece of leather. Hold that number in your head, because rind thickness is the single most reliable way to separate the common earthballs from one another.

Colour of the wall in section is whitish to cream, sometimes flushing pinkish or brownish where damaged. There is no gelatinous layer, no ring, no volva and no gills anywhere in the structure. An earthball is simply a closed bag of spores with a rind around it.

The spore mass and its colour sequence

The interior, the gleba, tells you how far along the fruitbody is, and it runs through a very specific sequence. In a young button it is firm and white or greyish-white, marbled with paler veins. As it matures it darkens dramatically to a purplish grey, then to a deep purple-black, still solid but crumbly, and it is that dark purple stage that people find most striking when they open one. Finally it dries out to a loose, powdery, olive-brown to dark brown dust with a few pale threads running through it.

Watch how the fruitbody opens. There is no neat pore. The top of the rind simply tears irregularly, splitting into ragged lobes that peel back and let rain and wind scatter the powder. Old specimens end up as shallow torn cups half full of brown dust.

The stalk-like base

Dig out the whole thing rather than pulling the ball off the ground. Below the fertile head there is a narrowed, sterile, stem-like extension that can be 1 to 4 cm long, wrinkled and paler than the head, sometimes furrowed. It is packed with tough tissue rather than spores, and in section you can see the boundary where the dark gleba stops and the pallid sterile tissue begins.

From the bottom of that base radiate stout white to yellowish cords, the rhizomorphs, which typically bind a mass of sand and grit into a ragged clump. This rooting, sand-gripping base is one of the most characteristic things about the species and is worth photographing in situ.

Flesh, cutting and colour change

The rind cut surface can flush faintly pinkish in some collections but does not go through a dramatic sequence of colours the way some relatives do. The mature spore powder will stain fingers and paper brown, and it darkens anything damp it touches. There is no milk and no latex.

The spore print question

A conventional spore print is not possible: there is no gill surface to lay on paper. What you do instead is take a pinch of mature gleba, tap it onto white paper, and read the powder in mass. It reads dark olive-brown to blackish-brown. Under a lens, the spores are globose and covered in spines. Whether those spines are joined into a net-like reticulum is a genuinely diagnostic microscopic feature, and in this species the spines stand largely free rather than forming a complete net across the surface.

Substrate and season

This species forms root partnerships with trees, so look near oak, birch, poplar, lime and beech, but specifically on the lighter, sandier, more disturbed patches of ground beneath them: path sides, bare banks, thin turf, sand pits and made ground in parks. It is far less a species of deep undisturbed woodland litter than of the open sandy margins. The main season is summer into late autumn, and it is often one of the earlier fungi to appear in a dry summer because the sandy sites it favours drain fast.

Separating it from the look-alikes

Common Earthball, Scleroderma citrinum. The obvious contrast. That species has a thick, corky rind, commonly 2 to 5 mm and sometimes more, breaking into coarse polygonal warts, a distinctly yellower ochre ground colour, and essentially no stalk at all: it sits squat on the ground on a broad attachment. Cut both in half and the rind thickness alone settles the question.

Leopard Earthball, Scleroderma areolatum. Closer, and genuinely tricky. It is usually smaller, with a thin rind, and its surface breaks into small dark scales set in a regular, cracked, leopard-spotted pattern of pale rings, more geometric than the irregular scattered scales here. Its sterile base is short and less developed. Microscopically its spores are spiny.

Scleroderma bovista and Scleroderma cepa. Both have far smoother, near-glabrous surfaces that lack the scaly patterning entirely. S. cepa is characteristically onion-like in shape, flushing reddish when cut, and S. bovista has spores whose ornamentation forms a distinct net.

Pisolithus arhizus. Superficially a lumpy brownish mass with a rooting base, but slicing it reveals the giveaway: the interior is divided into hundreds of small pea-like chambers embedded in a dark matrix, a structure no Scleroderma has.

True puffballs, Lycoperdon and Bovista. Very different in section. Their wall is thin and soft, often finely spined or granular on the outside, the young interior is pure soft white, and the mature fruitbody vents through a neat apical pore rather than tearing open. The dense, hard, purple-black gleba stage of an earthball is simply not something a puffball produces.

A quick field checklist

Sandy ground under broadleaf trees, a tan ball with small appressed dark scales that rub off, a rind under 1.5 mm thick, a marked stem-like sterile base with sand-bound cords, a gleba that runs white to purple-black to olive-brown, and an irregular tearing apex.