390 



THALLOPHYTES 



The most common and familiar members of the order are the 

 Puffballs, common in the woods and fields, and so named because 

 when pressed upon the spores puff out in cloud-like masses 

 (Fig. 346). Some of the Puffballs are a foot or more in diameter 

 when mature and most of them are edible. The sporophore 



FiQ. 345. — A Polyporus Fungus, Polyporm svlfureus, on the Red Oak. 

 It causes the Red Heart Rot of trees. Photo by Dr. W. A. Murrill, N. Y. 

 Botanical Garden. 



develops from a subterranean mycelium, and is differentiated 

 into an outer region which constitutes a two-layered skin-like 

 covering iperidium) and an interior chambered region {gld)a) in 

 which the basidia intermingled with sterile hyphae occur. Spores 

 are produced in immense numbers. A Puffball of ordinary size 

 produces many millions of spores. The spores are dark in color 

 due to their heavy walls. They escape from the sporophore 

 through pore-hke or slit-like openings in the peridium. 



