392 



THALLOPHYTES 



Fig. 348. —a Bird's 



Nest Fungus, Nidvlaria. 

 About natural size. 



organic matter in the ground. The sporophore is at first globose, 

 but the gleba soon breaks out of the peridium and is elevated to 

 some distance above ground by an elongating stalk. The spore 

 masses are slimy and have the odor of 

 carrion. Certain insects which dissemi- 

 nate the spores are attracted by the 

 odor. 



Smuts (Ustilaginales). — The Smuts 

 are parasitic Basidiomycetes. In some 

 Smuts, the mycelium, although evident 

 only in local areas, traverses widely 

 through the host, while in others only 

 local areas of the host are attacked. 

 No sporophores, .such as characterize 

 the Toadstools and Puffballs, occur in the Smuts. There are 

 more than 2000 species of Smuts. They attack chiefly plants 

 of the Grass family and espe- 

 cially the cereals, the grains of 

 which they commonly displace 

 with powdery black masses of 

 spores. The financial loss due 

 to Oat Smut alone has been 

 estimated to be $10,000,000 

 annually in the United States. 

 In addition to the loss due to 

 the destruction of the cereal 

 crops and the lowering of their 

 market price, there is consider- 

 able loss due to Smut explosions 

 in thrashing machines. During 

 the summer of 1914, 300 thrash- 

 ing machines were blown up or 

 burned in the Pacific Northwest 

 by Smut explosions. Smut dust 

 is highly combustible when dry, 

 and is probably ignited by static 

 electricity in the cylinder of the 

 thrashing machine. The Smuts are particularly destructive 

 to Oats, Wheat, Rye, and Barley. Corn Smut is exceedingly 

 common but less destructive. 



Fig. 349. — Stink Horn Fungus, 

 Phalljis impudicus. At the right, 

 vertical section of the P\uigus in 

 early stage of development, showing 

 the gleba enclosed by the peridium. 

 At the left, mature stage, showing 

 the gleba elevated much above the 

 peridium. X |. 



