Rosen: Behavior of Telia of Puccinia graminis 113 



the microscope showed spores of a typically normal type in size, 

 shape and color. The unique character of this telial material 

 contrasting strongly with lack of telial development on other 

 hosts and especially with material collected on the same day on 

 timothy in which no telia but a very heavy infestation of uredinia 

 was observed, made it appear worth while to study this Elymus 

 infection. Several times during the fall, winter and early spring 

 attempts were made to germinate the material collected on these 

 different occasions but always without success. Profuse ger- 

 mination was finally obtained from material collected on April 5. 

 This germinating material was smeared on young, moistened 

 leaves of Berberis trifoliolata Moric, on a potted plant growing 

 in the greenhouse, and the whole plant covered with a bell- jar 

 for forty-eight hours. Another plant, uninoculated, served as a 

 check. Reddish-yellow, cushion-like spots began to develop in 

 about six days, and in eleven days, numerous pycnia, mostly 

 epiphyllous, had developed. No infections developed on the 

 check plant. The pycnia were typical of Puccinia graminis and 

 the infections as a whole were similar to those obtained on the 

 same host infected by using germinating telia on wheat straw 

 coming from Iowa. (See Rosen and Kirby, loc. cit., p. 571.) It 

 should be added that the telia were viable on April 29 and that 

 on June 25 no germination was obtained. No data is at hand to 

 indicate to which specialized race the telia of Elymus australis 

 belong. Apparently this species of Elymus has not previously 

 been recorded as a host for P. graminis and material has accord- 

 ingly been deposited in the Arthur Herbarium. However, Stak- 

 man and Piemeisel (Jour. Agr. Res. 10: 429-495. 1917) list 

 various species of Elymus as congenial hosts for two specialized 

 races which attack wheat, the " biologic forms " tritici and tritici 

 compact^ for the one which attacks rye, secale, and for the oat 

 race, avenae, which appears only slightly infectious on Elymus spp. 



The telia on E. australis here recorded are of interest not only 

 because they differ from the ordinary behavior of stem rust telia 

 in this region, but because they clearly show that if telia are fully 

 developed they can be " overwintered " properly in this region 

 and that they are infectious. 



University of Arkansas, 

 Fayetteville, Arkansas. 



