72 



Jan. 1906] Cultures of Uredineae in 1905 21 



These results agree essentially with those reported by Carle- 

 ton,- 4 who was able to infect Xanthium in eighteen and fourteen 

 days, but could not infect Ambrosia. He says, however, that 

 "in all these cases spermogonia preceded the teleutospores in the 

 infected spots." In connection with an account of cultures with 

 Puccinia hctcrospora he adds that "numerous experiments were 

 also made with other lepto species, including Puccinia Grindeliae 

 Pk., P. variolans Hark., P. Lygodesmiae E. & E., and P. Sher- 

 ardiana Korn., with results similar to those above mentioned," 

 but he does not report the details of these cultures, if such they 

 were. 



Taking the observations here recorded for P. Xanthii, espe- 

 cially in connection with those for P. Silphii and P. Grindeliae, 

 reported below, it seems safe to assume that these species, and 

 those quoted as mentioned by Carleton, belong to a group of 

 rusts in which teleutospores and their resulting sporidia are 

 the only spore-forms produced in the life-cycle, aecidia, uredo, 

 and even spermogonia being wholly absent. 



The following nine species have never been tested before 

 by the culture method, so far as the writer knows, either in this 

 country or abroad. They embrace an interesting diversity of 

 habit. Besides the grass and sedge forms, with which this series 

 of cultures has been most concerned, there are two leptopucciniae, 

 one micropuccinia and one brachypuccinia, also one of the grass 

 rusts is chiefly interesting for its amphispores. 



1. Puccinia Silphii Schw. Teleutosporic material was 

 gathered March 31, 1905, near Lafayette, Ind., on dead and 

 weathered leaves of Silphium integrifolium, and sown April 10 

 on vigorous plants of the same host, and also on S. perfoliatum. 

 There was no infection on the latter host, but on the former 

 clear yellow dots showed April 15, which sectioned and placed 

 under the microscope proved to be very young teleutosori. 

 These yellow dots rapidly enlarged, forming pale pimples scat- 

 tered over yellow patches of the leaf, with much hypertrophied 

 tissues, and April 20 broke through the epidermis, exposing the 

 abundant teleutospores. Another sowing on the same two hosts 

 was made April 25, and with the same results : there was no 

 infection of S. perfoliatum, and the most abundant infection of 

 *S\ integrifolium, showing as yellow dots May 2, and exposed 

 teleutospores May 5. As the rust occurs on both these species 

 of Silphium, and many others as well, the results may be taken as 

 indicative of biological races. 



2. Puccinia Grindeliae Pk. Excellent teleutosporic ma- 

 terial on Guticrrezia Sarothrae was sent by Mr. Bethel, collected 



"Bulletin Bureau PI. Industry, No. 63:26. 1904. 



