54 



48 



Journal of Mycology 



[Vol. 11 



species of Helianthus were employed, on which to sow the 

 leleutospores. 



CULTURES OF HELIANTHUS RUST. 



Hosts for cultures 



1. H. annuus 



2. H. decapetalus . . . 



3. H. divaricatus . . . 



4. H. grosse-serratus 



5. H. hirsutus 



6. H. Kellermani . . . 



7. H. laetiflorus 



8. H. Maximiliani . . 



9. H. mollis 



10. H. occidentalis .. . 



11. H. orgyalis 



12. H. scaberrimus . . 



13. H. strumosus .... 



14. H. tomentosus . . . 



15. H. tuberosus 



Source of teleutosporic material 

 H. mollis H. grosse-serratus H. laetiflorus 

 ! ! ! 



! Abundant infection. 



; Infection, but slow growth and few or no aecidia formed. 



. No infection. 



- Not sown. 



The results of this year accord closely with those of 1902 

 and 1903. In 1902 some success was attained in sowing spores 

 from //. grosse-serratus on H. Maximiliani, but no success this 

 year. In 1903 sowing spores from H. mollis on H. strumosus 

 gave no infection, this year a few spermogonia were formed, but 

 no further development took place. In all other respects the 

 work of the three years is in perfect accord. Altogether sixty- 

 four sowings have been made. 



Looking over the accompanying table it will be seen that 

 each set of spores grew upon the species of host from which 

 derived, but not upon the other two species, except that spores 

 from H. laetiflorus sown on H. mollis gave a tardy showing of 

 spermogonia, without further development. Also each set of 

 spores grew luxuriantly upon H. annuus, and each made a feeble 

 growth upon H. tomentosus, but on all other species they either 

 failed to infect or made a feeble growth, with the single excep- 

 tion that spores from H. laetiflorus grew well on H. scaberrimus. 



From all results so far available, it seems that the following 

 conclusion may safely be drawn. Puccinia Helianthi Schw. is 

 a single species, having many races, for which H. annuus acts 

 as a bridging host. 



4. Puccinia subnitens Diet. Teleutosporic material of 

 this species on DisHchlis spicata (L.) Greene were sent from 

 Nebraska by Rev. J. M. Bates, to whom I am also indebted for 

 suggestions which led % to one of the most interesting series of 

 cultures yet made. In a communication dated April 30, 1904, 



