I From the Bulletin of thb Torrby Botanical Club, 39: 63-67, pi. 4. 9 Mr 1912. 



Studies in pyrophilous fungi — III.* The vitality of the spores of 



Pyronema 



Fred J. Seaver 

 (with plate 4) 



In the first paper of the present series, in attempting to impress 

 upon botanists the value of Pyronema as a plant to be used in 

 regular class study, it was stated that no data were at hand as to 

 the length of time during which the spores of this fungus would 

 keep their viability. As a knowledge of this point is of vital 

 importance in determining whether the teacher is able to tide 

 over this plant in the laboratory from year to year, it is deemed 

 worthy of special study and mention at this time. 



As has been previously stated, when once this fungus has been 

 cultivated it is comparatively easy to "get a catch" from the air 

 by simply exposing properly heated soil and keeping it moist for 

 a few days. Especially is this true in greenhouses. To my knowl- 

 edge, since this fungus has been under observation here, steamed or 

 heated soil used for planting in the propagating houses of the 

 New York Botanical Garden has never failed to develop the fungus. 

 Some time ago the spores of the fungus were sent to Purdue Uni- 

 versity for experimental purposes, and recently in a conversation 

 with Dr. F. D. Kern he informed me that this fungus also now 

 made its appearance in their greenhouse whenever heated soil was 

 exposed. While the fungus may usually be obtained in this way 

 when once it is started, this method is uncertain and the occur- 

 rence of the plant is likely to be delayed when it is most needed. 

 It is therefore better to develop and rely upon some more certain 

 methods of securing and preserving it. 



During the present winter the fungus was desired for study in 

 classes at Columbia University, and several pots of heated soil 

 were exposed to the air, as formerly, in the laboratories of the 



* Studies in pyrophilous fungi — II. Changes brought about by the heating of 

 soils and their relation to the growth of Pyronema and other fungi, was published in 

 Mycologia 2: 10Q-124. pi. 24-26. 1910. 



63 



