GRAMINEOUS CROPS. 



129 



the early autumn the uredo-mycelium produces blackish 

 spores, and when these spores are massed together they 

 give rise to the well-known sori of the com mildew. The 

 wheat stem and leaves become covered (more or less) with 



Fig. 45. — The Summer Wheat Mildew (Puccirda graminis). 



A. A section of a portion of a sorus of Fredo linearis (the early stage of P. 



gramiTiis) x 195. 



B. A section of a portion of a sorus of PucciTim jrammis .(later stage) x 195. 



C. Genoinating teleutospore. x 490. 



D. TJredospore (1), Teleutospore (2), Pro-mycelium spore (3). x 490. 



black disease spots belonging to the Puccinia, mildew, 

 or perfect state of this fungoid growth. If a transverse 

 section (Fig. 45 B) of one of the disease spots (sori) is 

 examined microscopically, a mass of two-celled spores 

 ;;teleutospores) will be observed. The teleutospores, like 

 the uredospores, are supported on erect hyphse rising 

 from a compact mycelium embedded in the tissues of the 



K 



