What You Should Know
Scleroderma citrinum is the most common species of earthball in woods, heathland and in short grass from autumn to winter.
Earthballs are superficially similar to, and considered look-alikes of, the edible puffball, but whereas the puffball has a single opening on top through which the spores are dispersed, the earthball just breaks up to release the spores.
Moreover, Scleroderma citrinum has much firmer flesh and a dark gleba (interior) much earlier in development than puffballs. This mushroom has no stem but is attached to the soil by mycelial cords. The peridium, or outer wall, is thick and firm, usually ochre yellow externally with irregular warts.
Spore mass inside mushroom white when very young easily differentiated from the thick white "rind;" soon mass turns black or purple-black, mottled with whitish lines; a blackish-brown powdery mass when mature; spores "puff" from top
Other names: Common Earth Ball, Pigskin Poison Puffball, Kartoffelbovist, Scléroderme vulgaire, Scléroderme orangé.
Scleroderma citrinum Mushroom Identification
Can be 4–12cm across and 3–6cm tall. The tough skin is dirty-yellow to ochre-brown and covered in coarse, warty scales in irregular shapes. As the fungus matures, it can turn ochre-brown or green.
The flesh inside a young earthball is whitish, sometimes with a pink-purple tinge. As it ages, the flesh becomes purple-brown to black with what looks like small white ‘veins’ running through it.
The spore mass is grayish, becoming purply-black, marbled at first by white veins and powdery when mature. The individual spores are spherical and spiked. When mature, the outer skin ruptures, creating a large, irregular opening that releases the spores which are then dispersed by wind and rain.
It doesn’t have a stem but does have a few root-like mycelial threads which are attached to the soil.
Not to be confused with
Scleroderma areolatum has much finer scales. Common earthball also resembles the edible puffball but doesn’t have an opening at the top like the puffball, is less spongy and the internal flesh is never pure white.
Scleroderma citrinum Taxonomy and Etymology
This fungus was first described in scientific literature by Christian Hendrik Persoon in 1801. (Persoon's Synopsis Methodica Fungorum, published in 1801, marked the starting point for a taxonomy of gasteromycete fungi.)
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 such as the Common Earthball are in fact close relatives of the boletes, and in particular boletes of the genus Gyroporus.
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 citrinum refers to the citrine (lemon-yellow) color of the skins of most Common Earthballs.
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