Leathery Puffball Identification Guide

First impression: a ball in open ground

Most puffball encounters happen in woodland, so the first thing that flags this species is the landscape. You are standing in open, sunny, well-grazed or disturbed ground when you notice a pale ball sitting on bare soil among short turf, usually 5 to 15 cm across and occasionally up to 20 cm. It often looks half sunk into the ground, with soil and sand adhering to the lower half.

Just as often you find last season's remains first: a stiff, weathered, bowl-like shell with thick curling lobes, sitting on the surface like a piece of discarded leather. Those persistent old shells are excellent evidence and are worth searching for deliberately, because they survive months of weather and tell you the species is resident in the field.

The setting that frames the identification

This is a fungus of dry, warm, nutrient-enriched open ground. Typical sites include grazed pasture, sheep-walk, cattle-trodden field margins, dune slacks and stabilised sand, steppe and semi-arid grassland, roadside verges and manured or heavily disturbed soil. It is a saprotroph living on rich organic material in the upper soil, so it favours ground where animals have concentrated nutrients.

It fruits after rain in warm periods, mostly late summer into autumn, and in warmer regions can appear opportunistically whenever a wet spell follows heat. Finding a large, thick-walled ball in short grass far from any trees is already a strong steer away from the woodland puffballs.

Step one: the outer skin

Work from the outside in. On a young specimen the outer layer, the exoperidium, is whitish to pale grey or cream, smooth to slightly felty, and often carries a crust of adhering sand and soil particles.

As the ball matures, that outer layer dries and cracks into flat, irregular scales and patches that flake away like old whitewash, revealing the layer beneath. This is not the pyramidal warting of an earthball or the fine spines of a Lycoperdon. It is a shallow, patchy exfoliation, and it leaves the ball looking mottled buff and greyish-brown.

Step two: cut one in half

This is the step that makes the identification, and it needs a knife. Slice a specimen vertically from top to base and look at the wall in cross-section.

The inner wall, the endoperidium, is unusually thick for a ball fungus: roughly 1 to 3 mm, and rigid. Between finger and thumb it feels corky and leathery, more like thin cardboard or a piece of old shoe leather than the paper-thin skin of Calvatia or the soft, spongy skin of Lycoperdon. It resists tearing, and when it does give way it splits rather than shredding. That combination of thickness and rigidity, judged by touch, is the single most useful character in the field.

Inside, the spore mass, or gleba, changes with age. Young material is white and firm, with a fine, uniform, chambered texture. It passes to cream and yellowish, then olive, then a deep purple-brown, and finally becomes a dry, dusty powder that occupies the whole interior. There is no substantial sterile base column of the kind that supports Calvatia excipuliformis; the base narrows to a small tuft of white to buff mycelial cords binding soil.

Step three: how it opens

The opening behaviour is the second signature character. A mature Leathery Puffball does not develop a neat apical pore. Instead, the rigid wall splits from the apex downward into a small number of coarse, irregular lobes or rays, which then curve outward and back like a thick, clumsy star. What remains is a stiff, persistent bowl of leathery segments holding the last of the spore dust, and that structure survives on the ground long after the season has ended.

Because the wall is so rigid, wind and rain empty it gradually rather than in puffs, and the segments stay recognisable for months.

Step four: reading the spores

You do not take a conventional spore print from a ball fungus. Instead, tap or squeeze a mature specimen over a sheet of white paper and read the colour of the dust: it is purple-brown to blackish-brown, with a faint olive undertone in less mature material.

Under a microscope, two features confirm the genus outright. The spores are globose, thick-walled and ornamented with coarse warts and short irregular ridges. More distinctively, the capillitium, the network of sterile threads running through the spore mass, is built of thick-walled brown filaments that are studded with short, stiff, thorn-like spines along their length. Nothing else in the temperate grassland ball fungi has spiny capillitium like that, and a single squash mount settles the question.

Separating it from the look-alikes

Calvatia and Handkea species such as C. utriformis and C. excipuliformis are the commonest grassland confusion. Their peridium is thin, flexible and papery, breaking up and blowing away, and C. utriformis has a distinctly woolly-scaly surface that fragments into a shallow persistent cup with soft, thin, ragged edges. Feel the wall thickness and the difference is immediate.

Calvatia gigantea is far larger and has a very thin, kid-like skin that flakes and disintegrates entirely, leaving no rigid rays.

Bovista species are small, smooth and papery, and the whole ball commonly detaches from the ground and rolls, opening by a small irregular tear.

Scleroderma species also have thick walls, but the wall is firm-rubbery rather than corky-leathery, and rarely more than about 2 to 5 mm even in the stoutest species. More usefully, earthballs grow in and around woodland as root partners of trees, are typically smaller, and pass through a distinctive marbled purple-black interior stage rather than a chambered white one.

True earthstars in Geastrum split into rays too, but the rays are the outer layer only, and they sit beneath a separate, thin, papery inner sac with a clearly defined mouth. The Leathery Puffball has no inner sac and no defined mouth: the splitting layer is the same layer that holds the spores.

Disciseda species are small, invert themselves, and carry a plaque of soil on top.

Tulostoma species sit on a slender distinct stalk.

A working field sequence

1. Note the habitat: open, sunny, grazed or disturbed nutrient-rich ground with no trees.
2. Note the size: a substantial ball, usually 5 to 15 cm.
3. Examine the outer skin for whitish felt cracking into flat flaking patches.
4. Cut it in half and judge wall thickness by touch: 1 to 3 mm and rigid.
5. Record the gleba colour stage: white, then olive, then purple-brown powder.
6. Look around for last year's split, curling, leathery shells.
7. If you have a microscope, check for spiny brown capillitium threads.