256 DISEASES OF FIELD & GARDEN CROPS. [CH. 



the crop has been destroyed by the presence of the 

 smut fungus. 



The general appearance of a panicle of oats affected 

 with smut is illustrated, natural size, at Fig. 117. In the 

 field it is evident that (as with bunt) the disease springs 

 direct from the root, for it is common to see numerous 

 stems, and every one diseased, springing from one base. It 

 is equally clear that the disease traverses each stem from 

 the bottom upwards, as the lower spikelets of the young 



FIG. us. 



Part of a spikelet of oats with Smut fungus, Ustilago carbc/j Tul. 

 Enlarged 5 diameters. 



panicle are the first to show the disease, as illustrated in 

 Fig. 117. Nothing is more common than to see the basal 

 branches of the panicle with their spikelets diseased and 

 the upper part of the panicle presenting the normal 

 healthy appearance. 



Part of a spikelet only slightly affected with the smut 

 fungus is illustrated in Fig. 118, enlarged five diameters. 

 AA are the glumes ; B, outer glumelle, sometimes fur- 

 nished with a beard or awn ; C, inner glumelle ; D, abor- 

 tive flower ; E, the pistil or grain. The interior of the 



