March 1905] Cultures oj Uredineae in 1904. O O 55 



Puccinia Stii*ae Arth. 



0. Spermogonia amphigenous, irregularly grouped, punctiform, 

 brownish orange, subepidermal, globoid, 95-110 /* in diameter; ostiolar 

 filaments free, 35-50^ long. 



1. Aecidia amphigenous, in irregular groups, on hypertrophied spots, 

 brownish orange, small ; peridia low, fragile and evanescent, cells abutted 

 or slightly imbricated, smooth outside, tuberculate inside, thin walled; 

 aecidiospores globose, 18-25 M in diameter, wall medium thick, 1-2 m, 

 brownish yellow, closely and finely verrucose, pores many, scattered, often 

 conspicuous. 



On Aster multiHorus Ait., Iowa and Kansas, and also cultivated 

 on A. ericoides L., and A. Novae-Angliae L. 



4. Puccinia Sorghi Schw. Through a fortunate observa- 

 tion in the field, June 2, 1904, upon finding aecidia on Oxalis 

 cymosa Small, the attempt was made to grow the aecidiospores on 

 young* corn plants, which resulted in complete success. On 

 June 2, aecidia-bearing leaves were suspended over potted corn 

 plants, under a large bell jar. On June 10 uredosori broke 

 through the epidermis, and on July 10 teleutosori began to appear. 

 This is taken as demonstrating the genetic connection of Mcidiv.m 

 Oxalidis Thuem. and Puccinia Sorghi Schw. 



A detailed account of this culture, with citation of all collec- 

 tions of the aecidium on various species of Oxalis, known to the 

 writer, has already been published in the Botanical Gazette (38 -.64- 

 67. 1904). 



5. Puccinia Podophylli Schw. This autoecious species 

 of rust is very common in the vicinity of Lafayete, Ind. Leaves 

 bearing recently opened aecidia were placed above the leaves of 

 two potted plants on May 7, and both kept under bell-jars for 

 three days. On May 23, one plant began to show teleutospores, 

 and, on May 20, the other plant exhibited many whitish spots 

 which began to burst open and display teleutospores on May 24. 

 Both plants proved to be heavily infected over large areas of the 

 leaves. 



The principal interest in this culture comes from the fact that 

 the sowing of aecidiospores did not give rise to secondary aecidia, 

 but exclusively to the characteristic teleutospores. Sydow in his 

 Monog. Uredinearum (1 1526) states that this species has primary 

 and secondary aecidia, the former being more common and form- 

 tended groups, the latter coming later with the teleutospores 

 and are sparsely distributed with few together in small groups. 

 As many similar species of rusts have repeating aecidia, it would 

 be natural to suppose that in this case the secondary generation 

 arose from the aecidiospores of the first generation. The culture 

 was made from a luxuriant development of the primary form ; and 

 from the fact that no secondary aecidia appeared, I think it can 

 be safely assumed, that the so-called secondary generation arises, 

 generally at least, from teleutospores, and its sparse distribution is 

 due to the smaller number of sporidia which strike the leaf, or to 



