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TEXTBOOK OF BOTANY 



Smuts and rusts. Seed plants of many kinds, particularly the grasses, 

 are infected by parasitic fungi that are unlike those just described. 

 Owing to their appearance, some of them are referred to as rusts; others 

 as smuts. The importance of these fungi in decreasing crop yields will be 

 discussed in the next chapter. Here we shall describe the growth and 

 reproduction of a few characteristic species. The vegetative and floral 

 parts of oats, wheat, rye, corn, rice, and onions sometimes contain black 



Fig. 249. Effects of smuts of cereals: A and B, loose smut of oats; C, covered 

 smut of oats; D, enlarged and distorted "corn grains" filled with smut. Photos 

 from U. S. Department of Agriculture. 



or dark brown masses of fungous spores (Fig. 249). These masses are 

 generally regarded as the smut plants, but thev are merely the reproduc- 

 tive structures of an extensive mycelium within the host. Several types 

 of smuts may be exemplified by the loose and covered smuts of oats, the 

 loose and stinking smuts of wheat, the loose and covered smuts of barley, 

 and bv the corn smut. 



Bunt or stinking smut of wheat. At threshing time mature spores of the 

 fungus may stick to the surface of the wheat grains and remain there 

 until the grains are planted.- At that time the spores gemiinate in the soil 



- The spores may also fall to the ground, germinate, and grow saprophytically in the soil 

 for a short time only. Each spore produces a short hypha that forms se\eral "sporidia." 



