A puffball is a member of any of a number of groups of fungus in the division Basidiomycota. The puffballs were previously treated as a taxonomic group called the Gasteromycetes or Gasteromycetidae, but they are now known to be a polyphyletic assemblage. Their distinguishing feature is that they have gasterothecia (gasteroid basidiocarps) in which the spores are produced internally; that is, the basidiocarp remains closed, or opens only after the spores have been released from the basidia. The spores of puffballs are statismospores rather than ballistospores, meaning they are not actively shot off the basidium. They are called puffballs because a cloud of brown dust-like spores is emitted when the mature fruiting body bursts. Puffballs and similar forms are thought to have evolved repeatedly (that is, in numerous independent events) from hymenomycetes by gasteromycetation, through secotioid stages. Thus Gasteromycetes or Gasteromycetidae are now considered descriptive terms (more properly gasteroid or gasteromycetes) and not valid cladistic terms.
Puffballs encompass the genera Calvatia, Calbovista, Lycoperdon. The true puffballs, of the Lycoperdales, do not consist of a visible stalk (stem). Avoid the genus Scleroderma which have a young purple gleba. The stalked puffballs, of the lycoperdales, do have a stalk which supports the gleba. None of the stalked puffballs are edible as they are tough and woody mushrooms. The Hymenogastrales are the false puffballs. A gleba which is powdery on maturity is a feature of true puffballs, stalked puffballs and earthstars. False puffballs are hard like rock or brittle. No false puffballs are edibles as they are tough and bitter.
Puffballs were traditionally used in Tibet for making ink by burning them vigorously, grinding them, then putting them in water and adding glue liquid and "a nye shing ma decoction", which, when pressed for a long time, made a very black dark substance which was used as an ink.
The giant puffball, Calvatia gigantea (earlier classified as Lycoperdon giganteum), reaches a foot (30 cm) or more in diameter, and is difficult to mistake for any other fungus. It has been estimated that a large specimen of this fungus when mature will produce around 7 × 10¹² spores. If collected before spores have formed, while the flesh is still white, it may be cooked as slices fried in butter, with a strong earthy, mushroom flavor. It can often be used in recipes that would ordinarily call for eggplant. It does not store well in a freezer - the entire freezer rapidly acquires a strong mushroom smell.
To identify mushrooms may be stalked, without stalk, or false.