20 Raymond J. Pool 



Wabash, Weeping Water, Wood River, Grand Island, Or- 

 leans, Kennedy, Long Pine, Scotia. 



This is our most variable species of the Erysiphaceae. It is 

 most common and most variable with us on Polygonum avicularc. 

 However it is also quite common on Clematis virginiana. 



This paper constitutes the first publication in recent years deal- 

 ing with a' particular group of the local fungus flora with keys 

 and specific descriptions. It must not be supposed for a moment 

 that the above treatment contains the limit of our knowledge of 

 the Erysiphaceae of Nebraska. It represents merely the sum of 

 our present knowledge of the group, and in this way an attempt 

 has been made to put the already known facts in regard to the 

 group before the botanists and mycologists of the state. It is 

 hoped that the paper may constitute the nucleus about which 

 future and more systematic studies may be made, until sometime 

 not far distant we may issue a fairly complete treatment of the 

 Erysiphaceae of the state. I doubt not that there are other 

 species of the group not mentioned here to be found in the state. 

 Certainly the list of host plants will be considerably enlarged by 

 future study. Probably not all of the present existing hosts for 

 the various species have been listed here, but if not, it is be- 

 cause they have not been reported or placed in the Survey Her- 

 barium or in the general fungus collection which contains all of 

 the important exsiccati, and which have been studied during the 

 preparation of the present treatise. 



The enthusiastic and untiring work of Rev. J. M. Bates shows 

 what the collector out in the state may do in extending the 

 knowledge of the local flora. After many years' study of the 

 seed plants of the state he undertook to learn something of the 

 fungi. He has learned much during the years in which he has 

 made extensive collections. Much of the information as to range 

 and hosts of the various species in the above pages should be 

 credited to him. 



It is planned to publish as rapidly as possible progress re- 

 ports on various groups of fungi for the state until the whole 

 of the fungus flora shall have been studied. The writer solicits 



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