CH. XX.] 



GRASS MILDEW. 



127 



fruit of the mycelium was at one time considered a perfect 

 fungus, and was described under the name of Oidium moni- 

 lioides, Lk. The meaning of Oidium has been already ex- 

 plained, and monilioides means necklace-like, and refers to 

 the growth of the fungus, which resembles a string of beads. 



X-2 



FIG. 55. GRASS MILDEW. 

 Wheat Stem invaded 

 byErysiphe graminis, 

 D.C. Twice the na- 

 tural size. 



X-400 



FIG. 56. 



Oidium monilioides, Lk. The early condition 

 of Erysiphe graminis, D.C., enlarged 400 

 diameters. Germinating conidium enlarged 

 1000 diameters. 



The Oidium is extremely common on the Graminece in the 

 summer, and it may always be found on grass, and especially 

 rankly growing grass in damp positions. The necklace- 

 like growth of the beadlike conidia is so delicate that the 

 slightest touch or breath destroys their cliainlike arrange- 



