fungi from the group of Gasteromycetes. There are about 100 species, primarily from three genera: Lycoperdon, Bovista, and Calvatia. They grow in meadows, pastures, and forests. The fruiting body of puffballs can reach very great size—for example, one species of Calvatia can be the size of a large watermelon and contain up to 7 trillion spores, which are released when the cover bursts. Young fruiting bodies are edible. Puffballs must be distinguished from the inedible common earth-ball (Scleroderma). In the early stages the fruiting bodies of both are white inside; in true puffballs they yellow and then turn brown, while in common earth-balls they turn black or violet.