142 DISEASES OF FIELD & GARDEN CROPS. [CH.XXI. 



spores give rise to the Uredo if placed on 

 certain grass leaves. In the next chapter will be found 

 a description and illustration of the ^Eddium. 



Before dismissing Pucdnia Rubigo-vera, D.C., we may 

 say that Uredo and Pucdnia spores often, though not in 

 this species, grow together in the same pustules, and that 

 P. Rubigo-vera, D.C., and P. graminis, Pers., often grow in 

 company on the same leaves and stems. These parasites 

 divert the material which should go to the production of 

 good ears of grain for their own support ; they therefore 

 cause the general growth of corn to be weak and the ears 

 to be small in proportion to the virulence of the attack: 

 the straw, too, is not only damaged, but is made the 

 means of carrying the disease over the winter for the 

 following season. A variety of P. Rubigo-vera, D.C., 

 termed P. simplex, Kor., also occurs. The teleutospores 

 in this plant consist chiefly of a single cell, similar to the 

 single-celled examples of P. m-ixta, FL, illustrated in the 

 left-hand spore in Fig. 14. P. simplex, Kor., has also 

 been described as a species under the name of P. Hordei, 

 Fl., and P. anomala, Rost. 



Pucdnia Rubigo-vera, D.C., occurs in Europe on Cala- 

 magrostis ISpigejos, Roth. ; Arrhenatherum elatior, L. ; Holcus 

 mollis, L. ; H. lanatus, L. ; Avena flavescens, L. ; Festuca 

 elatior, L. ; Serrafalcus secalinus, Bab. ; Bromus mottis, L. ; 

 Secale cereale, Walld. ; B. arvensis, L. ; B. asper, L. ; Triti- 

 cum vulgare, VilL ; Lolium temulentum, L. ; Hordeum vul- 

 gare, L. ; H. distichum, L. ; H. murinum, L. ; and H. 

 secalinum, Trin. 



Suggestions for preventing and destroying the mil- 

 dews of corn are adverted to in the chapter where the 

 evidence for the connection of Pucdnia and JEddium is 

 reviewed. 



Pucdnia Rulngo-vera, D.C., is the same with P. stra- 

 minis, FL, and P. striasformis, West 



