7 



ai'ril] BOTANICAL GAZETTE 274 



10. Puccinia Vilf^: A. & H. 



This species of rust, better known as P. Sydowiana Diet., is 

 necessarily restricted in the vicinity of Lafayette to the few 

 localities where the host, Sporobolus longifolius? is to be found. 

 My attention was called to the fact by Miss Lillian Snyder that in 

 such localities the exceedingly common upright verbenas were 

 richly covered with AZcidium verbenicola K. & S., and with no 

 other species of aecidia in the vicinity. Going over the ground 

 myself, I found that the verbena plants, Verbena stricta being 

 particularly abundant, were more thickly studded with aecidia 

 the closer they stood to tufts of rusted Sporobolus, and that 

 fifty feet away from such source of infection they would be 

 entirely free. 



Cultures were undertaken in 1898, but too late in the season 

 to secure results. In the mean time a morphological resem- 

 blance was observed between the spores of Aicidium verbe?iicola 

 and the uredospores of Pucciiria Vilfce, that gave another hint 

 at genetic relationship. Both sorts of spores were approxi- 

 mately obovate, with colorless walls, greatly thickened at the 

 apex, and papillose instead of echinulate. Successful cultures 

 have shown that these rather uncommon characters meant more 

 than a coincidence in this case. It is the first time, so far as the 

 writer knows, that any significant resemblance has been pointed 

 out between the spores of aecidia and uredo of the same species. 



For some unexplained reason I was unsuccessful in germi- 

 nating the teleutospores of P. Vilfce, although they were taken 

 a number of times directly from the field. But with aecidio- 

 spores the results were ample and convincing. The dates are as 

 follows : 



May 31, yEcidiospores from Verbena stricta on Sporobolus longifo litis ; June 



10, uredo. 

 June 9, i^cidiospores from Verbena stricta on Sporobolus longifolius ; June 



21, uredo. 



3 Since this paper was read I have discovered that the grass under observation 

 was Sporobolus longifolius (Torr.) Wood, instead of S.asper, as given in the manuscript, 

 and printed in Science 10 : 565, and Proc. A. A. A. S. 48 : 299. The latter grass does 

 not grow in this region. 



