234 



Mycologia 



and aecia June 2, both in abundance, thus confirming the work of 

 1905 and 1906. 14 



6. Puccinia angustata Peck, on what was probably Scirpus 

 cyperinus (L.) Kunth, the plant showing only leaves but grow- 

 ing with plants with fruit, gathered at Spirit Lake, Iowa, by 

 the writer, was sown April 13 on Lycopus communis Bickn., giv- 

 ing rise to pycnia April 25, and aecia May 3, both in abundance. 

 It was sown again May 2 on Lycopus americanus MuhL, giving 

 rise to an equal abundance of pycnia May 11, and of aecia May 

 19, the interval between the appearance of pycnia and aecia being 

 exactly the same as in the first culture. 15 The result is interesting 

 in connection with an observation made by the writer while on an 

 excursion in the vicinity of Ithaca, N. Y., June 30, 1906. An 

 abundance of rusted Lycopus communis was gathered, with 

 uredinia appearing on close-by plants of Scirpus cyperinus, while 

 plants of L. americanus and 6\ atrovirens growing intermixed 

 were both quite free from rust. The field observation seemed to 

 indicate a biological difference between the rust occurring on the 

 two species of Scirpus and the associated Lycopus, and with a 

 view to experimental tests healthy plants of L. communis from 

 the Ithaca locality were sent to the greenhouse at Lafayette, the 

 species not occurring in Indiana or Iowa. These were the plants 

 used in the present cultures. The results seem to warrant the 

 tentative conclusion that P. angustata within some geographical 

 areas is inclined to form races confined to certain hosts, while in 

 other geographical areas the differentiation into races does not 

 occur, a condition that appears to arise in other species as well, 

 e. g., Puccinia subnitens Diet. 



7. Puccinia subnitens Diet., on Distichlis spicata (L.) 

 Greene, was available in two collections from Delaware, two 

 from Nebraska and two from Nevada, representing three areas 

 approximately on the fortieth parallel of latitude, but twelve 

 hundred miles between stations in longitude. The Delaware sta- 

 tion is on the Atlantic sea coast ; the Nebraska station is midway 

 of the continent on the great plains, with the Allegheny range of 



14 For previous cultures see Jour. Myc. 12: 23. 1906; and 13: 197. 1907* 



15 For previous cultures see Bot. Gaz. 29: 273. 1900; Jour. Myc. 8: 53. 

 1902; 11: 58. 1905; 13: 196. 1907; and 14: 14. 1908. 



