HYMENOGASTRALES 



- Additions to the U. S. Phalloidei. Bull. Torrey Bot. 

 Club, 7 : 29, 30. 1880. 



Order g. HYMENOGASTRALES. 



This order contains a few subterranean genera, most of which 

 are Californian and none of which are common eastward except 

 a single species of Rhizopogon which is abundant in some places 

 in the southern states. The plants are tuberous and grow just be- 

 neath the surface of the soil, often in sandy places where they are 

 frequently exposed by rain erosion. 



The genera of the single family Hymenogastraceae which are 

 found in the United States, may be known as follows : 



1. Peridium wanting or obsolete ; spores longitudinally striate. GAUTIERIA. 

 Peridium distinct. 2 



2. Peridium easily separable. 3 

 Peridium not easily separable. 4 



3. Spores elliptic or lanceolate, smooth. HYSTERANGIUM. 

 Spores globose, echinate at maturity. OCTAVIANA. 



4. Peridium surrounded by creeping threads of mycelium. 5. 

 Peridium thin, silky villous, with little mycelium or none ; spores ovate 



or fusiform. HYMENOGASTER. 



Peridium woolly, fleshy, compact; spores sphe.ical, rough. 



SCLEROGASTER. 



5. Peridium thick, somewhat leathery ; spores elliptic, hyaline. 



RHIZOPOGON. 



Peridium thick, tow-like ; spores ovate or elliptic, colored at ma- 

 turity. MELANOGASTER. 



Very few of the species are commonly known and of the dozen 

 species reported from California many if not most are known im- 

 perfectly from a single collection. Gautieria and Sclerogaster 

 have each a single Californian species ; Octaviana and Hymcno- 

 gaster have each two representatives in California, and the re- 

 maining genera have each three species, all Californian except 

 two species of Rhizopogon and a single species of Melanogaster 

 from South Carolina. On account of the subterranean habit o 

 the species they are not easy to discover and many other forms 

 are likely to be found. It is probable that there is some relation 

 between the climate and their distribution and they are to be 



