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2 BOTANICAL GAZETTE [JULY 



two records^"^ of any Uredineae being found on these hosts in 

 South America, both given as P. Phragmitis, which I have had 

 no opportunity to verify; and there is no record of such occur- 

 rence in Central America, Mexico, or the West Indies. 



The parasitism of the Uredineae is so intimate that, when it is 

 noticed that the three genera of hosts here studied belong to 

 three widely separated sections of Gramineae, strong proof should 

 have been required to show that any one species of rust could 

 inhabit them all. In determining unnamed material the follow- 

 ing key, based upon distinctions of host, position on the host, 

 and the uredospores may prove serviceable. It is rare that some 

 search in almost any specimen, at whatever time of year it may 

 be gathered, does not disclose at least a few uredospores. The 

 teleutospores are not so distinctive. 



Chlorides : Spartina, 



Sori arising from soft tissues (intercostal), 



Uredospores with wall thin, colored, echinulate - U, acuminatus, 

 Uredospores with wall thick, pale, echinulate - - P. Distichlidis. 



Uredospores with wall thickened above, colorless, 

 tuberculate - - - _ . - - 



- P. Seymotinana 



Sori arising from hard tissues (supercostal), 



Uredospores with wall thickened above, colorless, 

 tuberculate ------- 



Festuce^e ; Phragmites. 



Sori amphigenous, uredosori without paraphyses, 



P. Fraxinata. 



Uredospores with four equatorial pores - - - P, rubella, 



Sori amphigenous, uredosori with paraphyses, 



Uredospores with indefinite, scattered pores - - P, st?ntlltnta* 



BAMBUSEiE : Arti7idinaria, 



Sori hypophyllous, uredosori without paraphyses, 



Uredospores with rather thick wall, echinulate - P, Arnndifianae* 



The four species on Spartina will shortly be published as 

 exsiccati in the fourth fascicle of Arthur and Holways's Uredineae 

 Exsiccatae ; and the two species on Phragmites will be published 

 somewhat later in the fifth fascicle of the same series. 



Purdue University, 



Lafayette, Indiana, 



" Hedwigia 35 : 288. 1896. Spegazzini's Fungi Arg. 1221. 1899. 

 reported on Phragmites from Argentine. 



Both 



