Brown Puffball Identification Guide

First Impression and Setting

Picture upland pasture: a sheep-grazed slope in hill country, a rushy field edge, a heathy moorland margin or a mountain grassland at several hundred metres. Among the short turf lie what look like white golf balls, sitting on the surface rather than growing out of it, sometimes singly and sometimes half a dozen scattered across a few square metres.

The first thing to test is the shape. This is a ball, not a pear, not a top and not a club. There is no stalk, no tapering sterile base and no rooting foot; the whole fruit body is a sphere or a slightly flattened sphere, 3 to 6 centimetres across, resting on the ground and attached only by a single slender cord at one point.

Slide a finger underneath and lift. A young specimen detaches with a small tug, leaving a tuft of white mycelial cord attached to the turf. That single point of attachment, with no stalk of any kind, is the opening character of the genus.

The Two Skins

Puffballs of this group have two wall layers, and reading them in sequence is most of the identification.

The outer layer, the exoperidium, is white, thin and smooth to very finely felted, and it may show faint cracks like the glaze on old porcelain. It is not spiny, not warted and not covered in the pyramidal warts and spines of some relatives. In young specimens this white skin is intact and the ball looks uniformly matt white.

As the fungus matures, that outer layer breaks up and flakes away in irregular patches, often starting from the top. What lies beneath is the diagnostic feature: a smooth, papery, distinctly shiny endoperidium in dark purplish brown, bronze or almost black, tough and slightly leathery to the touch. The transition specimens, half white and half dark, are the most photogenic and the easiest to name.

The Opening

Watch how the mature ball releases its spores. It does not develop a neat circular pore at the apex as many puffballs do. Instead the papery inner skin tears open in an irregular, ragged aperture at or near the top, which widens with weathering.

Once open, and here is a genuinely useful ecological detail, the ball frequently breaks free from its cord and is rolled around the field by the wind, puffing out spore clouds as it bounces. Old, blackened, hollow shells from previous seasons often persist among the grass through winter, and finding those empty cases in early spring is a good way to locate a colony before it fruits again.

Cutting Through: The Interior

Slice a fruit body cleanly in half from top to bottom. In a young specimen the interior, called the gleba, is pure white, firm, homogeneous and slightly springy, like fine foam rubber.

Now look at the bottom of the cut face, because this is where the key negative character sits. There is no sterile base. The white gleba runs right down to the bottom wall, with no chambered, spongy, differentiated cushion of tissue beneath it and no stalk-like column. Puffballs with a sterile base show a visibly different texture in the lower third; this species does not.

As the specimen ages the gleba passes through yellowish and olive shades to a dark, dusty purplish brown, and finally to a mass of loose powder threaded with fine capillitium fibres. Intermediate stages are the least useful for identification, so try to section one young and one old fruit body from the same patch.

Instead of a Spore Print

There are no gills or pores here, so a conventional spore print is not possible. The equivalent step is a puff test. Hold a mature ball a few centimetres above a sheet of white paper and squeeze gently: a plume of spore dust settles as a fine deposit whose colour can then be judged. In this species the mass colour is a deep olive-brown to purplish brown.

Under a microscope the spores are globose to broadly oval, roughly 5 to 6.5 micrometres in diameter, and many retain a long, colourless, tapering pedicel, the persistent remnant of the sterigma, up to about 10 or 12 micrometres in length. Those long tails, plus a capillitium built of separate, dichotomously branched units with tapering tips rather than a single tangled network, are what define the genus microscopically.

Substrate, Season and Ecology

The fungus is a saprotroph of grassland soil and turf thatch, living on dead organic matter among grass roots. It prefers unimproved, well-grazed pasture, upland and montane grassland, heathy edges and dune grassland, and it is more frequent in northern and western hill country than in lowland arable landscapes.

Fruiting peaks from late summer through autumn, though the developing balls can be found earlier in wet summers, and the tough dark shells persist long after the spores have gone. Because the mycelium is perennial in undisturbed turf, the same field is worth checking year after year.

Separating the Look-alikes

Bovista plumbea is the closest relative. It is smaller, typically 2 to 3 centimetres, its inner skin is a lead grey to bluish grey rather than purplish black, it favours lowland short grassland and its spores carry even longer pedicels. Size and the colour of the exposed inner ball will usually settle it in the field.

Lycoperdon species are the commonest source of error. They have a sterile base, so the fruit body is pear-shaped, top-shaped or clubbed with a narrowed stalk-like lower portion, they usually open by a defined round apical pore, their outer surface is spiny, warted or granular, and a vertical section shows a chambered sterile cushion beneath the gleba.

Lycoperdon pratense, the meadow puffball, grows in similar grassland but is flattened, has a distinct chambered sterile base and a persistent cup after the top has weathered away.

Calvatia utriformis is far larger, often 8 to 15 centimetres, has a coarsely cracked mosaic surface and breaks up into a persistent bowl of tissue, and again shows a well-developed sterile base.

Scleroderma species are ruled out by their wall alone. It is thick, hard, corky and often scurfy-scaly, the interior is a firm purplish black mass marbled with pale veins even when young rather than white, and they open by irregular splitting of a rigid rind.

Immature Agaricus and Amanita eggs are ruled out by sectioning: a vertical cut through those shows the outline of a developing cap, gills and stipe, whereas here the interior is uniform.

Compact Field Routine

Confirm a stalkless ball attached by a single cord; check for a white outer skin flaking to expose a shiny purplish black inner skin; confirm the absence of a sterile base in vertical section; confirm the ragged apical tear rather than a neat pore; note the upland grassland habitat and puff a mature specimen for a deep brown spore cloud.