249 

 A RARE UROMYCES 



Hy John L. Sheldon 



Repeated efforts were made during the spring of 1906 to find 

 the teleutospore stage of the rust producing Aecidiuni Jwustoni- 

 atuin Schw. on Hoiistonia cocridca L. Although a number of 

 species of rusts were found near the infected plants of Houstonia, 

 their aecidial stages are known to occur on other hosts, with the 

 exception of a Uromyces found on Sisyrinchhan graminoides Bick. 

 Whether this particular Uromyces on Sisyri)ichi7tin has an aecidial 

 stage is probably not known, and whether it has one on Hous- 

 tonia has not been definitely determined. 



Observations made in the field showed that the Uromyces 

 developed after the Aecidiiim had begun to mature and distrib- 

 ute its spores. After the uredospores on SisyrincJiitun had de- 

 veloped, other plants of Sisyri)ichmin near by were infected both 

 naturally and by placing pieces of the infected leaves over plants 

 that had not previously shown the rust. 



Five clumps of Houstonia, with aecidia on them, were trans- 

 planted beside plants of Sisyrinclmnn in localities where the 

 Uromyces had not been seen and where there were no plants of 

 Hoiistonia growing. After about ten days to two weeks, depend- 

 ing upon the atmospheric conditions, uredosori began to develop 

 on the Sisyrinchiums. Of course, there is a possibility that they 

 may have been infected from spores from some other source, but 

 the transplanting was done as carefully as possible. One can 

 never be certain that his fingers and clothing do not have spores 

 upon them, but future inoculations under control may prove that 

 the Aecidium of Houstonia and the Uromyces of this Sisyrinchium 

 are stages of the same rust. Both hosts have been transplanted 

 from the field to the greenhouse, and an attempt will be made 

 to secure the different stages of the rust by inoculation, both on 

 mature plants and seedlings. 



The Uromyces on the Sisyrinchium is evidently very rare, at 

 least in this form. It differs from the description of Uromyces 

 Sisyrinchii Mont, in having uredospores, in the shape of the 



