108 A Monograph of the Erysiphaceae 



Hosts. — Oshya Virg'uiica^ Uhmts alata^ U, Americana, U.fulva. 



Distribution. — North America : United States — Massachu- 

 setts, New York, North and South Carolina, Ohio, Michigan, 

 Indiana, Alabama, Illinois, Mississippi, Wisconsin, Missouri i^l^i), 

 Iowa, Kansas, South Dakota (151). 



Quite distinct from U, Bivouac^ its nearest ally, in the larger 

 pcrithecia, with more numerous appendages and asci. U, Bivouac 

 is frequently recorded as occurring in America, but this is incorrect, 

 and the specimens so named have proved (with one exception) to 

 belong to the present species. 



9. U. flexuosa Peck, [Figs 83, 84] 



U, flcxnosa Peck, Trans. Albany Inst. 7 : 215./. 10-12, 1872 ; 

 Sacc. Syll. Fung, 1 : 8. 1SS2 ; Burr & Earle, Bull. 111. State Lab. 

 Nat. Hist. 2 : 408. 1887 ; Atkins. Journ. Elisha Mitch. Sci, Sec. 

 7 : 66. 1891 ; Burr. ; Ell. & Everh. N. Amer. Pyren. 16. 1892. 



Exsicc: de Thiim. Myc. Univ. 2052 ; Ell. N. Amer. Fung. 



661; Rab.-Wint. Fung, Eur, 3658; ^Seym. & Earle, Econ. 



Fung. ii8a, ii8b; "^Ell. & Everh. Fung. Columb. 416. 



Hypophyllous, or sometimes amphigenous ; mycelium evan- 

 escent or under surface of leaf, but sometimes subpersistent in very 

 thin patches on the upper surface ; perithecia more or less scat- 

 tered, rounded-lenticular, 85-156 /i in diameter, averaging 100 /i, 

 cells distinct, averaging 17 fx wide ; appendages variable in num- 

 ber, 14-60, usually about 30, about equalling the diameter of the 

 perithecium, simple, colorless, and aseptate, hyaline, enlarged, and 

 abruptly flexuose upwards, becoming refractive and thick-walled, 

 and often rough below ; asci 4-11, broadly ovate, with a short 

 stalk, 50-58 X 30-38 tx ; spores usually 8, sometimes 7 or (rarely) 



6, 18-22 X 10 /i. 



'*The flexuose appendages are characteristic of this species. 

 They sometimes appear as if twisted like the blade of a screw- 

 auger'' (Peck, loc. cit.). 



Hosts. — Acscuhis argiita (386), A. flava (60), A. glabra, A. 

 Hippocastamim, A. Pavia. 



Distribution. — North America : United States — Massachu- 

 setts, New York, New Jersey, South Carolina, Ohio, Indiana, 

 Alabama, Illinois, ^lississippt (361), Missouri, Kansas (386). 

 Canada — Ontario. 



