REED: SPECIALIZATION OF PARASITIC FUNGI 357 



According to the various workers the specialized race Avenae 

 occurs on a wide range of hosts. Eriksson (41) lists it on twenty 

 species belonging to fourteen genera; Jaczewski (68) lists it on seven 

 species belonging to six genera; Carleton (25) records it on nineteen 

 species belonging to fifteen genera; Stakman and Piemeisel (149) 

 record it on thirty-three species belonging to twenty-one genera. The 

 specialized race Tritici is reported by Carleton on seventeen species 

 belonging to seven genera; Stakman and Piemeisel list it on thirty- 

 three species belonging to nine genera; Jaczewski lists it on six species 

 belonging to five genera; Eriksson records it on the four cereals and 

 states that this race seems less sharply fixed in its host relations than 

 any of the others. Stakman and Piemeisel report another race, 

 Tritici compacti, from the Palouse wheat region of western United 

 States. This race is reported on twenty species belonging to six 

 genera. The specialized race Secalis also occurs on a number of hosts, 

 Eriksson reporting it on eleven species belonging to five genera, 

 Jaczewski reporting it on six species belonging to four genera and 

 Stakman and Piemeisel recording it on twenty-three species belonging 

 to nine genera. According to Eriksson, Jaczewski and Carleton the 

 specialized race Agrostis occurs only on species of Agrostis, while 

 Stakman and Piemeisel report it on thirteen species of grasses be- 

 longing to ten genera. The specialized race Arrhenatheri occurs on 

 both Avena sativa and Arrhenatherum elatius. The races Airae, Poae, 

 Calamagrostis and Aperae are limited to species of a single genus. 



Eriksson and Henning (43) separated the timothy rust from the 

 black-stem rust and made it a distinct species, PucciniaPhlei-pratensis. 

 The separation was based largely on the fact that they were unable, 

 with one doubtful exception, to infect the barberry with teleutospores 

 from timothy. Other workers have made similar attempts but with- 

 out success. Stakman and Piemeisel consider it best to regard timothy 

 rust as a race of Puccinia graminis. 



Eriksson (34) reports successful inoculations with uredospores from 

 timothy on Avena sativa, Festuca elatior and Secale cereale, negative 

 results being obtained with Triticum vulgare and Hordeum vidgare. 

 Johnson (69) transferred timothy rust, using uredospores, to Avena 

 sativa, Arrhenatherum elatius, Dactylis glomerata, Festuca elatior, Poa 

 compressa and Secale cereale. Inoculations on thirteen other grasses, 

 including Triticum vulgare and Hordeum vulgare, gave negative results. 

 Stakman and Piemeisel (149), however, were able to infect eighteen 

 species of grasses belonging to thirteen genera, these including Avena 

 .sativa, Hordeum vidgare and Secale cereale, but not Triticum vulgare. 

 They regard this race as being closely related to the race Avenae. 



It may also be noted that Eriksson lists barley {Hordeum vulgare) 



