KEY TO THE MORE IMPORTANT GENERA OF GASTEROMYCETEAE 561 



or clusters of basidia. At maturity the whole gleba or portions of it 

 become a powdery mass of spores with only rudimentary or lacking 

 capillitium. Order Sclerodermatales 



Only family. Family Sclerodermataceae 



Medium-sized to small, not hypogeous at maturity or not at all. Hymenial cavities 



with definite lining of basidia. Toward maturity the tramal tissue 



surrounding each cavity encloses it in a thin or thick wall, producing 



separate structures called peridioles. Order Nidulariales 



Peridioles very numerous, with thin walls, escaping by irregular breaking of the 

 thin peridium. Family Arachniaceae 



Peridioles few, with thick hard walls. Peridium beaker-like, opening by rupture 

 of the diaphragm-like top, leaving the peridioles like eggs in a nest. 



Family Nidulariaceae 

 Small (up to 5 mm.), mostly growing on decayed wood or on manure, the whole 

 gleba being expelled as a single ball by the eversion of the inner layer 

 of the thick peridium which splits stellately at the top. Gleba with 

 many distinct hymenial cavities or these obliterated by the ingrowing 

 basidia. Order Sphaerobolales 



Only family. Family Sphaerobolaceae 



Medium-sized to large, epigeous, at least at maturity (a very few exceptions). 

 Gleba mostly with definite hymenial cavities, or these sometimes ob- 

 literated. At maturity the gleba becomes a dry powdery mass of spores 

 and capillitium, in one family the basidia also remaining intact. 



Order Lycoperdales 



Without stipe. Outer peridium shedding in patches or granules, inner peridium 

 mostly thin (thick in Mycenastrum) , opening by a mouth (ostiole) or 

 by breaking away in pieces. Columella sometimes present. 



Family Lycoperdaceae 



Without stipe. Outer layers of the peridium splitting and turning back stel- 

 lately. Inner peridium opening by an ostiole or falling away in pieces. 

 Columella mostly present. Family Geastraceae 



With stipe. Basidia lining definite cavities or these more or less completely 

 obliterated. At maturity the whole gleba except capillitium and spores 

 dissolving into a powdery mass. Family Tulostomataceae 



With stipe. Basidia occurring in clusters on glebal hyphae. At maturity the 

 basidia and their supporting hyphae are not destroyed but make 

 up, with the spores and capillitium, the powdery contents of the 

 sporocarp. Family Podaxaceae 



Key to the More Important Genera of Gasteromyceteae 



Family Protogastraceae. 



Single genus, United States. Protogaster 



Family Hemigastraceae. 



Single genus, Europe. Hemigaster 



Family Hynienogastraceae. 

 No percurrent columella. 



At maturity a single hymenial cavity with folded or lobed hymenial lining. 



United States. Gasterella 



At maturity many hymenial cavities. 



Peridium almost absent at maturity. Spores colorless or pale brown, spiny 

 or verrucose. North America, Australia. Gymnomyces 



