Scleroderma areolatum Ehrenb. - Leopard Earthball

Scleroderma areolatum, Leopard Earthball

Phylum: Basidiomycota - Class: Agaricomycetes - Order: Boletales - Family: Sclerodermataceae

Scleroderma areolatum, the Leopard Earthball, is similar in appearance to many other Scleroderma species and difficult, therefore, to identify from macroscopic characters alone. It is much smaller that the Common earthball Scleroderma citrinum and rather less frequently encountered - no doubt due at least in part to its smaller size and less conspicuous colouring.

Look out for this swarthy little gasteromycete fungus in damp places under broadleaf trees.

Scleroderma areolatum growing beside a birch log

Distribution

The Leopard Earthball Scleroderma areolatum is fairly common and widespread throughout of Britain and Ireland. These inedible (and possibly poisonous) fungi are found also throughout mainland Europe and in many parts of North America.

Taxonomic history

This fungus was first validly described in scientific literature in 1818 by German naturalist Christian Gottfried Ehrenberg (1795 - 1876), who gave it the binomial scientific name Scleroderma areolatum. That still remains its generally-accepted name.

Synonyms of Scleroderma areolatum include Scleroderma lycoperdoides Schwein.

The gasteromycetes are not close relatives but simply a group of fungi sharing the characteristic of producing spores within a sealed spherical, oval or pear-shaped casing. It turns out that Scleroderma fungi are close relatives of the boletes, and in particular boletes of the genus Gyroporus.

Etymology

The generic name Scleroderma comes from the Greek words scler- meaning hard, and -derma meaning skin. Earthballs certainly do have hard (and thick) skins. The specific epithet areolatum comes from the Latin noun areola, which means the small circular region around a nipple - a reference, therefore, to the pale annular region around each scale on the surface of this earthball - like the spots on a leopard, of course!.

Toxicity

There are conflicting reports as to whether Scleroderma areolatum is seriously poisonous; however, it is generally considered as at best inedible and likely to cause stomach upsets.

Identification guide

Scleroderma areolatum, Leopard Earthball, side view

Fruitbody

Typically 1.5 to 4cm acrossl, the rounded fruitbody has a short stalk connected to its substrate by white mycelial threads.

 

Scleroderma areolatum, Leopard Earthball, top view

The tough skin of the earthball is less than 1mm thick and initially white, cream or yellow and may turn ochre-brown or green as it ages; at maturity it is covered with dark scales surrounded with creamy-white annular areas giving it the appearance of spots similar to those of a leopard - hence the common name.

Interior of Scleroderma aerolatum

Gleba

Inside the earthball the spore mass is almost white at first but soon turns brown with white marbling before becoming purple-brown throughout and then becoming dry and powdery.

At maturity the skin ruptures leaving an irregular opening via which the wind and rain disperse the spores.

Spores of Scleroderma areolatum

Spores

Spherical, 10-15µm diameter, densely covered with spines up to 1.8µm tall which (in contrast with Scleroderma citrinum) are not reticulately connected.

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Spore print

Dark purplish brown.

Odour/taste

Odour not distinctive; tasting is inadvisable as this species may be poisonous.

Habitat

Mycorrhizal, found growing mainly in deciduous woodland.

Season

July to early December in Britain and Ireland.

Similar species

Earthballs are much less spongy than the various puffballs with which they are sometimes confused.

Lycoperdon perlatum, the common puffball, has pearly, pointed scales and is very spongy to the touch. It is club-like in shape has a rudimentary infertile stipe.

Lycoperdon mammiforme, another of the many puffball species, is white at first before its surface breaks up into large cream scales rather than warts; it, too, is more spongy and is more pear shaped, comprising a fertile ball on a spongy infertile stipe.

Reference Sources

Fascinated by Fungi, Pat O'Reilly 2016.

Pegler, D.N., Laessoe, T. & Spooner, B.M (1995). British Puffballs, Earthstars and Stinkhorns. Royal Botanic Gardens, Kew.

BMS English Names of Fungi

Dictionary of the Fungi; Paul M. Kirk, Paul F. Cannon, David W. Minter and J. A. Stalpers; CABI, 2008

Taxonomic history and synonym information on these pages is drawn from many sources but in particular from the British Mycological Society's GB Checklist of Fungi and (for basidiomycetes) on Kew's Checklist of the British & Irish Basidiomycota.

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