132 



Mycologia 



to have suggested the name of the genus, but no one has appar- 

 ently considered the matter of sufficient importance to warrant 

 investigation.* Since the most common species of the genus, 

 Pyronema omphalodes (Bull.) Fuckel, is one of the few dis- 

 comycetous fungi in which sexual reproduction has been demon- 

 strated, numerous papers have been written on this phase of the 

 subject, but in each case the matter of the occurrence of the 

 species is dismissed with a simple statement of the fact. Nor, 

 so far as known, has anyone taken the trouble to cultivate the 

 species under artificial conditions either for the study of repro- 

 ductive processes or in the attempt to gain information as to the 

 reasons for its common occurrence on burnt ground. 



The plants of this genus were first encountered by the writer 

 in 1904, when the above-named species was found to be very 

 common on burnt places near Iowa City, Iowa. Scarcely a burnt 

 place could be visited in and about woods in wet weather on 

 which this species was not found to be present and often in abun- 

 dance, the plants appearing on charcoal and ashes and the burnt- 

 over soil. While the individual plants are small, ranging from 

 one to two millimeters in diameter, they commonly occur in dense 

 confluent masses often covering a space of several inches, and by 

 reason of their bright color they might, in spite of their small size, 

 be counted among the more attractive forms of fungi. 



The second occurrence of this species to attract the attention 

 of the writer was during the fall of 1906 in the propagating 

 houses of the New York Botanical Garden, where it was found 

 to appear on soil sterilized with steam under a pressure of ten 

 to fifteen pounds. Here the plants occurred as usual, forming 

 rose-colored or salmon-colored sheets over the surface of the soil, 

 the groups of plants being surrounded by a cobweb of mycelium. 

 Under these conditions the plants seem to thrive for a time, but 



* Since this paper went to press a synopsis of the article below has come to 

 the attention of the writer showing that some of the conclusions drawn in 

 the present paper have been previously arrived at. Although the present 

 work was conducted without knowledge of this previous work and the line 

 of experimentation is different, the conclusions, so far as the work has gone, 

 are almost identical. 



Kosaroff, P. Beitrag zur Biologie von Pyronema confluens Tub, gleich- 

 zeitig ein Beitrag zur Kenntniss der durch Sterilisation herbeigefiihrten Ver- 

 anderungen des Bodens. Bot. Zeit. 66: 23. 1908. 



