When the Wolf Breaks Wind

Common puffballs Lycoperdon perlatum, copyright H. Krisp.

In an earlier post, I described the way in which the 'gasteromycetes' of historical fungal classifications have come to be expunged as a category. The enclosure of spore-producing structures within a contained fruiting body such as a puffball, instead of exposed on a membrane such as on the underside of a mushroom cap, is something that has evolved many times in fungal history. One possible suggestion for why this may occur is as a protection against moisture loss, allowing the fungus to thrive in drier or more exposed habitats than before.

In that earlier post, I also mentioned off-hand that one of the best known groups of 'gasteromycetes', the puffballs of the Lycoperdaceae, are in fact close relatives of some of the best known typical mushrooms in the Agaricaceae. Indeed, it appears that recent authors may go so far as to synonymise the two families. Puffballs emerge as globular fruiting bodies that become packed with spores as they mature, until one or more openings develop in the external skin of the fruiting body and allow the pores to escape. Supposedly many puffballs are quite edible if collected before the spores begin to develop, though I've never tried myself. Particularly sought in this regard is the giant puffball Calvatia gigantea whose fruiting bodies grow particularly large; supposedly, examples have been found over a metre in diameter and weighing up to twenty kilogrammes.

Giant puffball Calvatia gigantea, copyright Alan Wolf.

Dispersal of spores from puffballs may be achieved in a number of ways. In species found in habitats with more regular rainfall, such as species of the genus Lycoperdon, spores are spread by 'boleohydrochory' (Gube & Dörfelt 2011). '-Chory' means dispersal, '-hydro-' obviously means water, 'boleo-' I think may mean something like 'throw'. The puffball opens through a hole in the top, and drops of rain (or other sources of pressure such as being tapped by an animal) cause a puff of spores to be squeezed out. The water may then carry the spores away. The name Lycoperdon, as it happens, literally translates as 'wolf fart', and this is another one of those names I am completely at a loss to explain. The 'fart', obviously, refers to the appearance of the spore puffs, but what on earth do they have to do with wolves?

Tumbling puffballs Bovista pila, copyright Dan Molter.

Other puffballs may spread their spores via 'anemochory', dispersal by wind. This is particularly the case with species found in drier habitats. Some species, such as some members of the genus Bovista, exhibit a variation on this called 'geanemochory' in which the entire puffball becomes detached and blown about by the wind, with the spores escaping through openings in the external shell like pepper being shaken from a pepper-pot. Differences in dispersal method between puffball species are generally reflected by differences in their spore morphology. Hydrochorous species usually have strong ornamentation, with the outside of the spore being covered with warts or the like. These warts provide more surface area for the water to catch onto; they may also help prevent the spores from clumping together. In contrast, anemochorous species have spores that are smooth, making them more streamlined for being blown through the air or, particularly in the case of geanemochorous species, making them less likely to become trapped by hyphae or other structures inside the fruiting body itself and so facilitating their escape.

REFERENCE

Gube, M., & H. Dörfelt. 2011. Gasteromycetation in Agaricaceae s. l. (Basidiomycota): morphological and ecological implementations. Feddes Repertorium 122 (5–6): 367–390.