386 



THE RtJSTS OF NOVA SCOTIA. FRASER. 



This species was for some time confused with Phr. 

 subcorticium (Schrnk) Wint. (Phr. mucronatum Lk.). Peck 

 first called attention to a variation in the 

 number of cells. He states that "American 

 specimens generally have the spores more 

 opaque and with two or more septa than 

 the typical form. This variant form 

 might be called Var. americanum/' (N. 

 Y. State Mus. Kep, 28: 86). ' Dietel raised 

 the variety to specific rank under the 

 name of Phr. americanum. 



According to Arthur Phr. americanum 

 inhabits the north-eastern region of North 

 America along the Atlantic coast from 

 Maryland northward and north of the 

 great lakes, chiefly on Rosa blanda, R. 

 lucida, R. Sayi and certain cultivated 



Tqliospores of Phragmid- . . , . , ,. . /rr , 



ium americanum. varieties derived from these (Torreya 

 9:27. 1909). 



It seems to be common on the roses in this vicinity. Col- 

 lections of another stage of the rust were made but they were 

 lost in drying. The collection reported in Dr. MacKay's 

 Fungi of K S. (Trans. K S. Inst. of Science 12:124) as 

 Phr. subcorticium belongs here. 



Phragmidium imitans Arth. 



Phragmidium gracile Arth. 



0. Pycnia not observed. 



1. Aecia rounded, small, scattered, epiphyllous, soon 

 naked, yellowish. Aeciospores rounded, oblong, elliptical or 

 oval, 16-24 by 12-29/*; wall unequally thickened, echinulate; 

 paraphyses slender, long, clavate, hyaline, incurved. 



II. IJredinia hypophyllous, scattered, small, rounded. 

 Urediniospores elliptical or obovate, 12-16 by 20-24/x; wall 

 rather thick, colourless, echinulate ; paraphyses slender, clavate, 

 thin-walled, hyaline, about 13-22 by 55-80^, incurved. 



