?H 



Arthur: Nineteen Years of Culture Work 



pared for the North American Flora P. tomipara, P. Agropyri, 

 P. cincrea, P. alternans and P. obliterata, as well as P. triticina, 

 were placed under the one name of P. Clematidis (DC.) Lagerh. 

 It is considered a great advance to bring from the limbo of P. 

 rubigovera, six distinguishable species, some of them having a 

 considerable number of recognized races, and thereby making it 

 possible to relegate to obscurity some dozen or more names that 

 had previously been encumbering the literature of the rusts. 



In a somewhat similar way the American Carex rusts were in 

 utter confusion at the beginning of the cultures. They were quite 

 generally called Puccinia Caricis or P. caricina, no cultures with 

 American material having been made, and diagnostic characters 

 not having been well worked out. Altogether ten species were 

 grown during the culture period to show their full life cycle, and 

 in several of them a number of races was found, including the 

 one-celled Uromyces perigynius. Of course, being able to sepa- 

 rate these ten species made it possible to decide upon the identity 

 of other species, which were not actually grown. 



A view generally held when the culture work began was that 

 the hosts of an autoecious species, or of each of the two parts of 

 a heteroecious species, would be found to be closely related, 

 often, injdeed, to be but a single species, or genus, and certainly 

 always within a single family. Consequently it was felt that 

 when a grass or sedge rust was successfully cultured, the problem 

 about hosts for that species was practically solved. This com- 

 placent opinion was quite upset in the case of Puccinia subnitens 

 Diet, on Distichlis spicata, which in 1902 was first grown upon 

 C hen podium album. In 1904 Rev. J. M. Bates of Nebraska, 

 who had made the field observations and suggestions for this 

 combination, wrote that he had been continuing his observations 

 of this species and believed that it had aecia also on hosts belong- 

 ing to two other families, which seemed to the writer at the time 

 as most incredible. Tests, however, showed it would flourish on 

 species of Cleome, Lepidium, Sophia and Erysimum, as well as 

 on Chenopodium, compelling the admission that it would grow 

 " with equal vigor upon species belonging to three families of 

 plants," at the time being a " remarkable fact not known for any 



