Leopard Earthball

The Leopard Earthball is one of the smaller members of the genus Scleroderma, forming firm ochre-brown balls 1.5-4 cm across on damp woodland ground. Its name comes from the surface pattern: numerous small, dark reddish-brown to blackish scales, each surrounded by a paler ring or halo of the underlying skin, so that the ball appears spotted rather than uniformly warty.

Scleroderma is placed in the Boletales, and earthballs are recognisably different from true puffballs in several ways. The rind is tough and rubbery rather than papery, the interior turns dark and marbled while still firm instead of passing through a long white stage, and the ball narrows below into a short stalk-like base bound with white mycelial cords.

Within the genus, S. areolatum is distinguished by its small size, its thin rind, its neat leopard-spot ornamentation and its habit of growing on wet, mossy, often trampled ground rather than on dry banks.

Fruiting body

Globose to slightly flattened or pear-shaped, 1.5-4 cm across, firm and rubbery to the touch. The ground colour is ochre-brown to yellowish-brown or tan.

Surface

Covered in numerous small, flattened, dark reddish-brown to blackish scales, each ringed by a distinctly paler zone or halo of the rind beneath, producing the leopard-spotted pattern that gives the species its name. The scales are fine and evenly spaced, not coarse and cracked.

Rind and opening

The rind (peridium) is thin for the genus, around 0.5-1 mm thick, tough and leathery. It does not open by a neat pore but tears irregularly at the apex, eventually splitting back into a few ragged lobes.

Stipe and base

The ball narrows below into a short, wrinkled, stalk-like sterile base bound to the soil by conspicuous white to yellowish mycelial cords and rootlets, which often bring up a plug of soil when lifted.

Flesh and spore mass

The interior is white only very briefly in the smallest buttons, then quickly becomes firm and purple-black to blackish, marbled with fine whitish veins, and finally a dry blackish-brown powder. Spores in mass are purple-black to blackish brown; microscopically they are spiny without a net-like reticulum.

Grows on damp soil in broadleaf and mixed woodland, especially along mossy woodland tracks, path edges, ditch sides, damp clearings and streamsides. It is often associated with birch, oak, willow, poplar, beech and hazel, and is one of the earthballs most likely to be found on compacted, trampled, wet ground.

Widespread across Europe and North America and reported from temperate Asia. Fruiting is from summer through late autumn, sometimes appearing in numbers along a single stretch of path.

Scleroderma areolatum is ectomycorrhizal. Its mycelium forms a sheath over the fine root tips of broadleaf trees, and the fungus supplies water and mineral nutrients such as phosphorus in exchange for carbohydrates from the host. This partnership is why earthballs are tied to particular trees and why they often line woodland paths where roots run close to the compacted surface.

At maturity the tough rind cracks and weathers rather than puffing spores through a pore, so dispersal is slower and more dependent on wind scouring and physical disturbance. Earthballs are also known for their tolerance of poor, disturbed and heavy soils, and they frequently colonise woodland edges and made ground.

Scleroderma citrinum, the Common Earthball, is much larger (4-10 cm), sits directly on the ground with almost no stalk-like base, and has a thick rind 2-4 mm deep with coarse, irregular, cracked yellow-ochre warts rather than fine ring-haloed scales. Scleroderma verrucosum is similar in size to the Leopard Earthball but has a longer, more clearly developed stalk-like base and finer, scattered brownish scales without the crisp pale halos. Scleroderma bovista is nearly smooth or very finely scaly with a distinctly stalked base, and its spores carry a net-like reticulum under the microscope.

True Lycoperdon puffballs are altogether softer, with a thin white peridium, spines or warts that fall away, an interior that remains white and homogeneous for a long time, and a neat circular apical pore rather than an irregular tear.