10 BULLETIlSr 957^ U. S. DEPARTMElSrT OF AGEICULTURE. 



States under the name R. aureum. This appears to be the form most 

 common in cultivation in Europe, but the true R. aureum of the 

 Rocky Mountain region and the plains of the Columbia was evi- 

 dently introduced there soon after R. odoratum, if not at about the 

 same time. Pursh may have referred to living plants of true R. 

 aureum but we have no means of determining this. Lindley in 1828 

 made the new species R. tenuiflorum (now R. aureum) and says 

 "Clt. 1812," evidently meaning "cultivated in 1812." He had this 

 so definitely distinguished from our R. odoratum that his statement 

 is fairly conclusive that R. aureum actually was introduced into 

 England the same year as was R. odoratum. The agent introducing 



Fig. 9.— Outline map of the northeastern part of the United States, showiag (by black dots and cross 

 hatcMng) the known distribution of white-pine bhster rust in North America to and including 1915. 



R. aureum can not be determined beyond question. There appears 

 to be little doubt, because of the difficulty of communication at that 

 time, that both plants were carried from their native regions to the 

 eastern part of this country in the form of seeds. Cuttings may have 

 been sent to Europe but it is more likely that seeds were sent. Seeds 

 would not be likely to transmit a rust which does not attack the 

 fruit. It does not seem possible that a fungus like Cronartium 

 ribicola could be carried to Europe on these plants without becoming 

 established in the Eastern States. Moreover, these species of Ribes 

 apparently were introduced into Great Britain first. The fungus 

 was not known in Great Britain until 1892, long after it was prevalent 

 in other northern European countries. It appears that Cronartium 

 ribicola was carried to Great Britain on infected white pines from 

 northwestern Germany. The evidence appears to show that Cro- 



