482 IOWA ACADEMY OF SCIENCE 



On Ribes oxycanthoides L. (66). Varieties of gooseberry de- 

 rived from the American species show moderate infection 

 while some of its hybrids with the European gooseberry 

 show light infection. 



On Ribes rubrum L. (64). The common red currant seems 

 to be rather lightly infected. 



On Ribes sanguiucum Pursh. (178). This species was planted 

 on the station grounds in 1914. The first season it was 

 scarcely infected at all, but in 1915 the infection was very 

 severe. 



On Ca-rex macrocfiaeta C. A. Meyers. (251). 



On Carex mertensii Prescott. (250). 



On Carex sitchensis Prescott. (252) . This and the two species 

 above are moderately to rather severely infected. 



On Carex stygia Fries. (197). This sedge is very abundant 

 all over the Muskeg, and seems always to be heavily in- 

 fected with the rust. From an economic point of view, it 

 is by far the most important Carex host of the Puccinia 

 under consideration, and from it most of the infection of 

 the Ribes on and near the Experiment Station grounds 

 probably takes place. 



Puccinia poarum. Niessl. 



II — On Poa pratensis L. (166). Not very common. 

 Puccinia pygmaea Erikss. 



II — On Calamagrostis aleutica, Bong. (201 and 218). Fre- 

 quent, but only a small portion of the host plants seem 

 to become infected. 



REFERENCES. 



1. Mem. Acad. St. Petersb., VI, 2, 1832. 



2. Piper, C. 7., Flora of the State of Washington: Cont. U. S. Nat'l 



Herb., XI, 1906. 



3. Sudworth, Geo. B., Forest Trees of the Pacific Slope. U. S. Dept. 



Agri., Forest Service, 1908, p. 93. 



4. Anderson, J. P., Iowa Erysiphaceas: Proc. Iowa Acad. Sci., XIV, 



1907. 



5. Salmon, E. S., A Monograph of the Erysiphaceae: Mem. Torrey 



Bot. Club, IX, 1900. 



United States Agricultural Experiment Station, 

 Sitka, Alaska. 



