Some Northwestern Erysiphaceae 



By David Griffiths 



The following list is prepared from material wliich has been 

 accumulating since 1S92. It is based upon specimens from 

 South Dakota, Wyoming and Montana. The species recorded 

 from the two latter States are in the nature of incidental gatherings 

 which w^ere niadc while engaged in other work during the sum- 

 mers of 1897 and 1898 in company with either Mr. L. W. 

 Carter or Mr. T. A. WiHiams. Access has been had to the private 

 herbarium and collections of Mr. Williams, and several hosts and 

 one species are quoted from these collections. The list is by no 

 means even approximately complete for the region covered. It 

 is pubhshed simply as a preliminary list to which additions will 

 doubtless be made w^hcn other localities are visited. 



As might be expected from a know^ledge of the altitudinal and 

 climatic variations of the states mentioned, tlie species are exceed- 

 ingly variable In both macroscopic and microscopic characters. 

 These variations have been quite thoroughly worked out by Pro- 

 fessor T. J. Burrill in Ellis & Everhart, N. A. Pyrenomycetes, but 

 the variations here are In many cases still greater than recorded by 

 either him or Dr. Relun in Rabenhorst's Kr}'ptogamen Elora. I 

 find my material variable, especially in the extent of mycelial de- 

 v^elopmcnt and the usual microscopic measurements. In the 

 matter of appendages, character of the wall of the perithecium and 



number of spores and asci I find less variation from published de- 

 scriptions. 



As to the identity of the species recorded here, there are two 

 points regarding which there is some doubt. ErysipJic dehor- 

 accaruni growing on Bigclovia^ Lygodcsmia and Griuddia appears 

 to me to have some constant characters of its ow^n. This I find to be 

 the case in various exsiccatac w^hich I have examined as well as 

 In my own collections. The characteristics which appear to be 

 the most distinctive are the abundant development of mycelium 

 which gives a different appearance from the forms on the other 



(138) 



