THE SMUTS 



259 



SERIES I THE SIMPLER BASIDIA FUNGI, OR 



PR O TOBA S IDIOM YCE TES 



274. The smuts. The smuts (order Ustilaginales] are para- 

 sites which have the peculiar habit of attacking the floral parts, 

 and especially the ovaries, of various members of the grass 

 family. The hyphse fill these parts with a dense mycelium, 

 destroying the tissue of the host. Finally, most of the cells in 

 the mycelium take on heavy walls and become 

 resting cells, or winter spores, which form the 

 black powdery mass so characteristic of the 

 smut fructification. These resting cells sur- 

 vive the winter and germinate in the spring. 

 Each cell then puts forth a short filament 

 called the promycelium (Fig. 228, A), upon 

 which are developed a number of small spring 

 spores called sporidia, and these in some cases 

 germinate upon the sprouting host plants, as 

 in oats, putting forth filaments that enter the 

 host and develop a mycelium within, which 

 may not be noticed until the fructifications 



, , , T , . . , A, with spring spores 



appear in the floral organs. It is important (sporidia) attached ; 

 to note that the sporidia multiply rapidly by B < 



i i 



budding (Fig. 228, B), especially under favor- 



able conditions, as in heavily manured soils, 



and these buds, or conidia, will infect like the sporidia. These 



habits of budding led to the theory that the yeasts have been 



derived from the smuts. 



Various smuts. The corn smut is, perhaps, the most con- 

 spicuous form and very destructive. The infection in the corn 

 is local ; that is, the spore masses are formed close to the point 

 of entrance of the fungus. Any tender growing region is sub- 

 ject to infection. The corn smut can only be held in check by 

 burning the spore masses as soon as discovered and by avoid- 

 ing the use of manure, which gives favorable nutrition for the 



228. Promyce- 

 Hum of the corn 



smut (U stlla 9 

 Maydis) 



s P rin s 8 P res 



budding like yeast 



cells. After 

 Brefeid 



