Hedgcock & Hunt: Coleosporium 



307 



lected on Solidago bicolor, near Takoma Park, D. C, October 7 

 (no infected Asters present in either locality). Each collection 

 was used in inoculations the day after collection. The follow- 

 ing pines were inoculated : 2 Pinus caribaea, 3 P. contort a, 4 P. 

 coulteri, 1 P. edulis, 1 P. palustris, 4 P. radiata, and 7 P. rigida. 

 Of these, the following were infected, bearing pycnia on or 

 about December 24, 1920, and aecia about March 15, 1921 : 2 P. 

 caribaea, 2 P. coulteri, 2 P. radiata, and 2 P. rigida. 



No cultures could be made with pedigreed urediniospores from 

 plants of species of Aster as none were infected in our inocula- 

 tions with aeciospores. Urediniospores from infections on spe- 

 cies of Aster in nature are apt to be mixed with those from 

 infected species ,of Solidago which are nearly always present. 

 In fact, the writer has usually found species of Solidago com- 

 monly infected in 'nature, and those of Aster rarely. Most of 

 the species of Aster used in the inoculations were used because 

 they were found infected in nature, and because of their known 

 susceptibility. 



The results from the inoculations are somewhat surprising. 

 132 plants of species of Aster and 241 of species of Solidago 

 were inoculated with aeciospores from six species of pine from 

 the eastern United States, viz., Pinus echinata, P, nigra, P. 

 pungens, P. resinosa, P. rigida, and P. taeda. Of these, 142 

 plants of Solidago (59 per cent.) were infected and none of 

 Aster. From inoculations with pedigreed urediniospores grown 

 in the greenhouse on plants of species of Solidago, 19 plants of 

 Solidago (25 per cent.) out of 77 inoculated were infected, but 

 none of 19 plants of Aster inoculated were infected. These re- 

 sults may be interpreted in more than one way. It might be 

 assumed that all the plants of Aster used were either from re- 

 sistant species, or were not in proper condition for infection, 

 neither of which is borne out by the facts, since many susceptible 

 species were selected both of Aster and Solidago, and more than 

 half of the plants were in splendid growing condition when in- 

 oculated. A more plausible explanation is that in the eastern 

 United States we either have two races of Coleosporium soli- 

 daginis, the one on species of Solidago, the other on species of 



