228 



Mycologia 



upon the wheat leaves. On May 29 urediniospores began to 

 show, and their abundance increased for some time, but owing to 

 the lateness of the season the wheat plants did not flourish, and 

 in consequence teliospores were not formed. 



This species of rust, which is the most injurious cereal rust 

 known, is very common throughout the country, not only on 

 cereals, but on many wild grasses. It has now been grown-^ in 

 our series of cultures from telia on- A gropyron repens from Ver- 

 mont, A. tcncriim from Iowa and Nebraska, Agrostis alba from 

 Indiana and New York, Cinna arundinacca from Indiana, Elymus 

 canadensis from Iowa and Wisconsin, and the two hosts men- 

 tioned above. In 1907 the aeciospores raised from telia on 

 Agrostis alba obtained in Indiana were used to produce infection 

 on wheat (Triticum viilgarc) and barley (Hordeum vulgare)^ 

 and in 1908 aeciospores raised from telia on A gropyron teneriim 

 obtained in Nebraska were used for infection on oats (Avena 

 sativa). This year the aeciospores raised from telia on Sitanion 

 longifoliuin obtained in Colorado produced infection on wheat. 

 More extended work is planned in regard to the problem of the 

 transfer of this pernicious black or stem rust from wild grasses 

 to the cultivated cereals, but enough has been accomplished to 

 warrant the statement that although in the uredinial stage this 

 rust shows racial strains that inhibit the ready transfer from 

 one species of host to another, as has been shown by many 

 European and American investigators, yet in the aecial stage 

 racial strains play no part, and the barberry acts as a bridging 

 host between each and every other gramineous host. 



13. PucciNiA suBSTERiLis E. & E., ou Stipa viridula Trin., col- 

 lected April 16 at Eldorado Springs, Colo., by Mr. E. Bethel, 

 bore abundance of amphispores, which were sown April 29 on 

 plants of Stipa viridula, and gave rise to urediniospores in abund- 

 ance, first observed May 24. A sowing at the same time on Stipa 

 spartea gave no infection. 



14. Uromyces Andropogonis Tracy, on Andropogon virgini- 

 ciis L., collected at Morgantown, W. Va., by Dr. John L. Sheldon 

 was sown June 4 on Viola cucnllata, giving ten groups of pycnia, 



For previous cultures see Jour. Myc. 8: 53- 1902; 11: 57, 1905; 12: 17. 

 1906; 13: 198. 1907; and 14: 16. 1908. 



