Scleroderma citrinum

Scleroderma citrinum, commonly known as the common earthball,^[1] pigskin poison puffball,^[2] or common earth ball,^[3] is a species of earthball fungus.

Scleroderma citrinum
Scientific classification
Domain:	Eukaryota
Kingdom:	Fungi
Division:	Basidiomycota
Class:	Agaricomycetes
Order:	Boletales
Family:	Sclerodermataceae
Genus:	Scleroderma
Species:	S. citrinum
Binomial name
Scleroderma citrinum Pers.

Scleroderma citrinum Mycological characteristics
	Glebal hymenium
	No distinct cap
	Hymenium attachment is not applicable
	Lacks a stipe
	Spore print is purple-black
	Ecology is mycorrhizal
	Edibility is poisonous

SEM image of a cross section of peridium, gleba region with small spiky spores

Description

The fruit bodies grow to 10 centimetres (4 in) broad and 6 cm high with a yellowish peridium, or outer skin.^[4]

Earthballs are superficially similar to, and considered look-alikes of, the edible puffball (particularly Apioperdon pyriforme), 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, S. citrinum has much firmer flesh and a dark gleba (interior) much earlier in development than puffballs. Scleroderma citrinum has no stem but is attached to the soil by mycelial cords. The peridium is thick and firm, usually ochre yellow externally with irregular warts.

Distribution and habitat

Found in Europe and in North America, it is the most common species of earthball fungus in the United Kingdom and occurs widely in woods, heathland and in short grass from autumn to winter. S. citrinum has two synonyms, S. aurantium (Vaill.) and Scleroderma vulgare Horn.^[5]

Ecology

Scleroderma citrinum is an ectomycorrhizal fungus with a symbiotic relationship with some tree species, and can influence the diversity of soil bacterial communities under some tree species.^[6]

The earthball may be parasitized by Pseudoboletus parasiticus.

Toxicity

Scleroderma citrinum is poisonous^[4] and can be mistaken with truffles by inexperienced mushroom hunters. Ingestion of S. citrinum can cause gastrointestinal distress in humans and animals. Some individuals may experience lacrimation, rhinitis and rhinorrhea, and conjunctivitis from exposure to its spores.^[7][8]

Pigments found in the fruiting body of S. citrinum Pers. are sclerocitrin, norbadione A, xerocomic acid, and badione A.