192 



MORPHOLOG Y. 



407a. Teleutospores the last stage of the fungus in the season. The teleu- 

 tospores are developed late in the season, or late in the development of the 



host plant (in this case the 

 wheat is the host). They 

 then rest during the winter. 

 In the spring under favor- 

 able conditions each cell of 

 the teleutospore germi- 

 nates, producing a short 

 mycelium called a promy- 

 celium, as shown in figs. 

 222, 223. This promy- 

 celium is usually divided 

 into four cells. From each 

 cell a short, pointed pro- 

 cess is formed called a 

 " sterigma. " Through this 

 the protoplasm moves and 

 forms a small gonidium on 

 the end, sometimes called 

 a sporidium. 



408. How the fungus gets from the wheat back to the barberry If these 

 sporidia from the teleutospores are carried by the wind so that they lodge on 



Fig. 220. Fig. 221. 



Germinating uredospore of Germ tube entering the 



wheat rust. (After Marshall- leaf through a stoma. 

 Ward.) 



Fig. 222. Fig. 223. Fig. 224. 



Teleutospore g e r m i - Promycelium of ger- Germinating sporidia entering leal 

 nating, forming promy- minating teleutospore.- of barberry by mycelium, 

 celium. forming sporidia 



Figs. 222-224. Puccinia graminis when' ni t\ ( A "ter Marshall- Ward.) 



