CHAPTER XXX. 



FUNGI (Continued). 



THE BASIDIUM FUNGI (CLASS BASIDIOMYCETES). 



The Smuts.* 



456. General characters. The smuts are a group of fungi 

 parasitic chiefly on the flowering plants. The mycelium lives in 

 the interior of its host. The spores have usually rather thick 

 brown walls, and are usually produced in great masses in the 

 fruiting part or stems of the host, after the mycelium has con- 

 sumed these parts. These masses break down into a fine dark 

 powder mixed with the minute dark spores, which gives a 

 smutted appearance to the affected parts of the host. 



457. The corn smut, j The corn smut (Ustilago ze<z) is one 

 of the most common and conspicuous species of the smuts. 

 Nearly every field of Indian corn shows a number of examples and 

 often many plants are affected. It forms large excrescences on 

 the ears, the tassel, the joints of the stem, and even on the leaves. 

 These are at first whitish, but later become black as the spores 

 ripen. The masses of smut then are often very large. The 

 spores in this smut-mass are rounded, minute, spiny bodies. 

 When these spores germinate a short hypha or germ tubej is 

 formed which has a few cross walls. Small elongated spores are 

 formed on the sides of this hypha near the joints or cross walls 

 (fig. 254). These are called sporidia. When these sporidia fall 



* The smuts are not true basidiomycetes. The promycelium formed by 

 the germination of the smut spore is believed by some to be an elementary, 

 or "beginning," basidium. If so, the smuts would belong to the basidium 

 series representing very low forms of the same. 



j- To THE TEACHER. The corn smut may be used for the practical work 

 and others may be introduced for comparison. 



1 Called here a promycelium. 



20 305 



