Lycoperdon pyriforme Schaeff. - Stump Puffball

Phylum: Basidiomycota - Class: Agaricomycetes - Order: Agaricales - Family: Agaricaceae

Lycoperdon pyriforme - Stump Puffball

Lycoperdon pyriforme, the Stump Puffball, is one of the most gregarious of all fungi. The banana of the fungi world, its bunches create impressive vistas sometimes stretching way into the far distance in woodlands where thinning has taken place and the lopped branches have been left for Mother Nature (mainly in her mycological guise) to dispose of. These pear-shaped fruitbodies are often seen swarming over dead stumps. (If they appear to be growing on soil this is not so but simply an indicator of buried trunks or branches.)

Lycoperdon pyriforme, Stump Puffball, Caledonian Forest, Scotland

The Stump Puffbals pictured above are young and fresh, whereas those on the left have darker outer surfaces and the spores masses inside them will have began maturing. At this stage these fungi will have become inedible.

Distribution

A widespread and very common find in Britain and Ireland, the Stump Puffball fruits most often in large, densely-packed groups on decaying tree stumps and sometimes on well-rotted fallen branches. Lycoperdon pyriforme is a worldwide fungus; its distribution includes mainland Europe and Asia as well as North America.

Taxonomic history

This edible fungus of the forests was first described in scientific literature in 1796 by Jacob Christian Schaeffer, who gave it the binomial name Lycoperdon pyriforme. That name was subsequently ratified by Christiaan Hendrik Persoon in 1801 and therefore remains its accepted scientific name today.

Lycoperdon pyriforme, Stump Puffball, Wales - mature specimens

Synonyms of Lycoperdon pyriforme include Lycoperdon pyriforme var. excipuliforme Desm.and Lycoperdon pyriforme ß tesselatum Pers.

Etymology

The genus name Lycoperdon literally means 'wolf's flatulence' and just begs the question who got close enough to a wolf and stayed there long enough to become an expert on such matters. For most of us, surely such an odour cannot be a practical diagnostic feature for identifying the Stump Puffball, Lycoperdon pyriforme.

Nothing at all to do with funeral pyres, the specific epithet pyriforme comes from Latin and simply means pear shaped.

Identification guide

Stump Puffballs on a buried log

Description

Typically 1.5 to 4cm across and 3 to 4cm tall, the pestle-shaped to pear-shaped fruitbody of the Stump Puffball is initially covered in short pyramidal warts. At first white, the skin turns brown and a dark area develops at the apex, which ultimately opens to release the spores. The fruitbody is attached to the substrate - usually the stump, half-buried rotting branches or roots of a dead tree - by means of long, white mycelial filaments extending deep into the substrate.

Stem

The short, spongy stem is usually more or less parallel or slightly conical tapering in towards a truncated base; it contains infertile material that remains white even when the gleba in the 'head' of the fungus has matured and turned dark olive-brown.

 

Spores

Round or subglobose, smooth, 3.5-4µm in diameter.

Spore mass

Olive-brown, eventually becoming dark brown when fully mature.

Odour/taste

Unpleasant gas-like odour; taste not distinctive.

Habitat & Ecological role

Saprobic, found growing mainly on stumps and roots of dead trees, usually hardwoods but occasionally on softwoods too. Stump Puffballs may appear to be growing on soil, but there is always rotten wood or decaying woody debris just beneath the surface. (The Stump Puffball is the only puffball species in Britain and Ireland that grows on wood rather than on soil.)

Season

July to early December in Britain and Ireland.

Similar species

Lycoperdon perlatum is usually somewhat larger, and it is covered with much larger pearly warts.

Lycoperdon mammiforme is white at first before its surface breaks up into large cream flakes that fall away to leave a fairly smooth pinkish-buff surface.

Lycoperdon pyriforme, Stump Puffball, on buried timber, Wales

Culinary notes

Like many other puffballs, these fungi are edible only if picked when young and white throughout. They are easily gathered because of their habit of growing in dense clumps, but being of only mediocre they are not much sought after. Nevertheless these common woodland fungi can make a nice meal if prepared and cooked properly. The first and most important step is to remove the tough outer skin - a fiddly job perhaps best done with a sharp knife. Choose only fresh young fruitbodies which, when cut in half along the vertical axis, are white all through. Discard any that have begun turning yellow, olive or brown, as this indicates that the spores are maturing and the flavour will be seriously marred if you include them in your dish. One of the best meals that you can make with these puffballs is a mushroom omelet; they can also be fried with onions or used to make soups.

Toxic imposters

A note of caution for newcomers to fungal foraging: there are ball-shaped fungi known as earthballs, and some of them can look quite similar to Stump Puffballs; however, their spore-bearing inner material starts off pale grey and gradually becomes dark grey, brown or black as the spores mature. Earthballs of any kind are inedible and some of them can cause serious poisoning. The most common of these, found on woodland tracks (and therefore sometimes close to Stump Puffballs), is Scleroderma citrinum, the Common Earthball. The differences in features between puffballs and earthballs are quite obvious once you know what to look for, but it is important to learn how to distinguish these two groups if you plan on gathering edible puffballs for the pot.

There are also some poisonous gilled mushrooms which, when young, could be mistaken for Lycoperdon pyriforme, the Stump Puffball. Amanita muscaria, the Fly Agaric, first appears as a white-warted round button - the red cap skin does not show through until the cap has expanded somewhat - and at that stage it could quite easily be mistaken for a puffball. Even more seriously, the infamous Deathcap, Amanita phalloides, starts off as a rounded button mushroom, sometimes pure white or with just the faintest hint of olive. I mention this simply to emphasise how important it is not merely to learn how to identify a range of the finest edible mushrooms but, equally importantly, to become familiar with the identifying characteristics of the poisonous fungi with which they could be confused.

For more help with this important safety matter see Fascinated by Fungi; however, some introductory information on edible fungi with toxic imposters is online here...

For a very easy to recognise edible puffball that cannot be mistaken for any other mushroom, see Calvatia gigantea, the Giant Puffball. Unfortunately it's not every day that you stumble across Giant Puffballs, as they are not only uncommon but also very localised in their distribution. If you find a good spot for these mighty meaty meal sources, make a note of it because Giant Puffballs can reappear in the same places for many years.

Reference Sources

Fascinated by Fungi, Pat O'Reilly 2016.

Pegler, D.N., Laessoe, T. & Spooner, B.M (1995). British Puffballs, Earthstars and Stinkhorns. Royal Botanic Gardens, Kew.

Dictionary of the Fungi; Paul M. Kirk, Paul F. Cannon, David W. Minter and J. A. Stalpers; CABI, 2008

Taxonomic history and synonym information on these pages is drawn from many sources but in particular from the British Mycological Society's GB Checklist of Fungi and (for basidiomycetes) on Kew's Checklist of the British & Irish Basidiomycota.

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