REED: SPECIALIZATION OF PARASITIC FUNGI 363 



same lack of specialization to particular hosts as Carleton reports for 

 the crown rust in the United States. 



Puccinia glumarum (Schm.) Eriks. and Henn. Eriksson (34) is 

 the only investigator to report on the host relations of this rust. He 

 claims the existence of five specialized races: 



1 . Tritici on Triticum vulgare. 



2. Secalis on Secale cereale and Triticum vulgare. 



3. Elymi on Elymus arenarius. 



4. Agropyri on Agropyron repens. 



5. Hordei on Hordeum vulgare. 



Puccinia dispersa Eriks. and Henn. Ericksson (34, 40) first 

 separated the hosts of this rust into five distinct groups each sup- 

 porting a distinct specialized race. Later each race was raised to 

 specific rank, based on the host relations and life history. 



1 . Secalis on Secale cereale. This race has its aecidial stage on different 



species of Anchusa. 



2. Agropyri on Agropyron repens {Puccinia agropyrina Eriks.). 



Aecidial host unknown. 



3. Bromi on Bromus species {Puccinia hromina Eriks.). According to 



Miiller (99), this race has its aecidial stage on Pulmonaria mon- 

 tana and Symphytum officinalis. 



4. Tritici on Triticum viilgare {Puccinia triticina Eriks.). Aecidial 



host unknown. 



5. Hold on Holcus lanatiis and H. mollis {Puccinia holcina Eriks.). 



Aecidial host unknown. 



6. Triseti on Trisetum flavescens {Puccinia Triseti Eriks.). Aecidial 



host unknown. 



Miiller, Ward, and Freeman have studied the rust of the bromes. 

 Miiller (103) found that aecidiospores from Pulmonaria montana 

 infected Bromus arvensis, B. brachystachys, B. erectus, B. mollis and 

 B. secalinus. Aecidiospores from Symphytum officinalis also infected 

 these species of Bromus and, in addition, B. brizaeformis. Miiller 

 obtained the following results with uredospores: (i) uredospores from 

 Bromus erectus infected B. arvensis, B. brachystachys, B. erectus, B. 

 macrostachys and B. mollis; (2) uredospores from B. arvensis infected 

 B. arvensis, B. brachystachys, B. inermis and B. mollis; (3) uredospores 

 from B. mollis infected B. brachystachys, B. macrostachys and B. mollis. 



Ward (171, 172) has carried out a large series of experiments with 

 this rust. In his inoculation tests he used species of Bromus belonging 

 to each of the five recognized subdivisions of the genus. Uredospores 

 from eleven different species, belonging to three different sections of 

 the genus, were used. Ward found marked differences in the sus- 

 ceptibility of the bromes to the uredospores from different hosts. In 



