202 Journal of Mycology [Vol.13 



2. Uromyces on Juncus tenuis. — This rust, which has 

 generally passed under the name of Uromyces Junci, is very com- 

 mon in the United States east of the Rocky Mountains from 

 Canada to the Gulf of Mexico. It is often highly parasitized, 

 so that the sori contain few or no well grown teliospores. A 

 number of attempts to bring the rust under culture have failed 

 because the teliospores could not be made to germinate. In 

 1902 a sowing was made on Iris virsicolor without success. 



Unparasitized material on Juncus tenuis Willd. was found 

 near Lafayette, Ind., April 3, that proved to be viable, and was 

 sown April 20 on Lactuca canadensis, L. virosa, Senecio obo- 

 vatus, Rudbeckia laciniata, Ambrosia triUda, A. artemisiaefolia, 

 and Silphium perfoliatum. Much to our delight pycnia were 

 observed on the last host April 30, and were followed by a great 

 abundance of aecia May 7. Another sowing was made May 4 

 on vS". perfoliatum and S. terebinthinaceuni, and the next day on 

 Partheniuni intcgrifolium. Only the first was infected, showing 

 pycnia May 17, and May 31. The plant of S. terebinthinaceum 

 was weak and did not grow well. Later sowings May 9 on 

 Polymnia canadensis, and June 5 on Pathenium intcgrifolium 

 and Silpkimn terebinthinaceuni, gave no infection. 



Another collection of teliospores on Juncus tenuis was sent 

 by Dr. John L. Sheldon from Morgantown, W. Va., which was 

 found close to Houstonia caerulea bearing aecia. This material 

 was sown May 19 on Houstonia caerulea, H. purpurea and 6"//- 

 phium perfoliatum. No infection occurred on the Houstonias, 

 but pycnia appeared on the Silphium May 29, and aecia June 

 4, both abundant and well formed. 



Since obtaining the unequivocal cultural results, a morpho- 

 logical study has been made of the rust, which clearly demon- 

 strates that it is specifically distinct from Uromyces Junci 

 (Desm.) Tul. As it appears never to have been recognized as 

 an autonomous species, the following name and description are 

 submitted : 



Uromyces Silphii (Syd.) nom. nov. (Accidium conupositarium Sil- 

 phii Burr. Saccardo, Syll. Fung. 7:798. 1888; Accidium Silphii Sydow, 

 Uredineen 1546.) 



0. Pycnia chiefly epiphyllous, in small groups, golden brown, sub- 

 globose or ellipsoid, subepidermal, 80-100 M broad by 80-110 /* high; osti- 

 olar filaments up to 65 m long. 



1. Aecia amphigenous, in groups 4-10 mm. across, crowded about 

 the pycnia on discolored spots, deep-seated, short, 0.2-0.4 mm. in diameter; 

 peridium colorless, margin recurved, lacerate, peridial cells rhombic, 20-28 M 

 across, outer wall thick, 6-8 M, transversely striate, inner wall thinner, 

 4-6 M, moderately verrucose ; aeciospores angularly globoid, small, 13-18 M 

 in diameter, wall colorless, thin, about 1 m, minutely verrucose. 



On Silphium intcgrifolium Michx., Illinois (type, McLean County, 

 May .3, 1881 or 1882. A. B. Seymour 4852, recorded in Burrill's Parasitic 

 Fungi of Illinois, page 231), Wisconsin; 5". terebinthinaceum Jacq., Illi- 



