Leathery Puffball

The Leathery Puffball is unmistakable once mature. Instead of the thin, papery skin of most puffballs, it has a thick, tough, corky-leathery wall two to three millimetres deep, which does not flake away but splits open into stiff, irregular, star-like lobes that curl back and persist for months as a rigid bowl on the soil.

Mycenastrum is a small genus with a single widely recognised species. It is set apart from Calvatia, Bovista and Lycoperdon not only by that heavy peridium but also by microscopic characters: the capillitium threads are thick-walled and covered in short spines, and the spores themselves are conspicuously warted or spiny.

The species is a fungus of open, dry and often heavily disturbed ground, and turns up in places where livestock congregate. Fruiting bodies commonly reach 5-15 cm across and are hard and heavy compared with other puffballs of similar size.

Fruiting body

Globose to somewhat flattened or irregularly lumpy, 5-15 cm across and occasionally larger, often partly buried in the soil when young so that it appears to rise up out of the ground.

Skin layers

A thin whitish felty outer layer sloughs away in patches to reveal the endoperidium: a thick, rigid, corky to leathery wall, whitish then dull ochre, greyish or brownish. At maturity this wall cracks and splits from the top into broad, irregular, star-like rays or lobes that peel back stiffly, leaving a rigid bowl full of spore powder.

Attachment and stipe

No stalk. The base is broad and attached to the soil by coarse mycelial strands, and the empty rind often remains rooted in place after the spores have blown away.

Flesh and spore mass

The interior is white and firm at first, then olive, and finally a dense purple-brown to blackish-brown powder. Microscopically the capillitium is thick-walled and spiny and the spores are strongly warted, both distinctive for the genus. Spores in mass are purple-brown.

Grows on soil in open, sunny, often disturbed places that are rich in nitrogen: manured pasture, stockyards and corrals, cattle-trampled ground, field margins, irrigation banks, roadsides and desert flats after rain. It has a marked preference for dry to semi-arid climates and alkaline or saline soils.

The species is scattered but widespread, recorded from western and central North America, southern and eastern Europe, central Asia, South America, Africa and Australia. Fruiting follows rainfall in summer and autumn, and the split, weathered rinds persist for a long time afterwards.

Mycenastrum corium is saprotrophic, decomposing dung-enriched organic matter and plant debris in the upper layers of open soil. Its association with corrals and grazed ground reflects that nutrient preference rather than any partnership with plants.

The heavy peridium is an adaptation to a harsh, exposed environment: it protects the developing spore mass from drying wind and sun, and when it finally splits, the stiff upright lobes hold the spore powder in an open cup where wind can scour it away gradually. The rigid remains can go on shedding spores long after the season ends.

Calvatia puffballs of similar size have a thin peridium that weathers, flakes and disintegrates into fragments rather than splitting into thick rigid rays, and they usually have a spongy sterile base. Earthstars in the genus Geastrum also open into star-like rays, but there the rays are the outer layer peeling back from a separate, thin-walled inner spore sac with a well-defined mouth, whereas in Mycenastrum the single thick wall itself splits and there is no distinct inner sac.

Scleroderma earthballs have a tough rind but it is thinner, warty or scaly on the surface, and it cracks irregularly rather than opening into broad star-like lobes; their interior turns marbled purple-black at an early stage while still firm.