16-i A Monograph of the Erysiphaceae 



Distribution. — North America : United States — Vermont, New 

 Hampshire, Massachusetts, New York> West Virginia (249), Ohio, 

 Indiana, Illinois, Wisconsin, Missouri, Iowa, Washington. Canada 



— Ontario, 



Very distinct among the species of the genus in the long flac- 

 cid colored appendages. The nature of the final branching of the 

 apex of the appendages is very hard to see in M. RiisscUiiy as in 

 this species, as in many of the genus MicrospJicray the appendages 

 arc extremely slow in arriving at maturity, and perithecia are fre- 

 quently found in which the asci and spores are formed, although 

 the appendages are still unbranched. Figs. 38, 39 represent the 

 most branched form of the apex of the appendages that I have 

 seen. Burrill (60) says '' appendages simple, bifid, or two or three 

 times irregularly branched, branches long, often distorted, tips not 

 swollen or recurved." 



9. M. EUPHORBiAE (Pcck) Bcrk. & Curt. 



Erysiphc ciiphorbiae Peck, Reg. Rep. 26: 80. 1874; Sacc. 

 Syll. Fung. 1:18. 1S82, 



MicrospJiacra euphorbiac Berk. & Curt. Grcvillea, 4 : 160. 

 1876 ; Sacc. Syll. Fung, i : 13. 1882 ;^Burr. & Earle, Bull. HI- 

 State Lab. Nat. Hist. 2: 41S. 1887; Atkins Journ. Elisha 

 Mitch. Sci, Soc. 7 : yo, pi. i,f. 1-4., 1891 ; Burr.; Ell. 8c Everh. 

 N. Amer. Pyren. 26. 1892. 



M, colutcac Kom. Scripta Bot. Hort. Univ. Imp. Petropol. 4 : 

 270. 1S95. 



Exsicc: Ell. N. Amcr. Fung. 431; Rab.-Wint. Fung. Eur, 



3246; Jacz.-Kom.-Tranz. Fung. Ross. Exsicc. 79. 



Amphigenous ; mycelium usually subpersistent, thin and ef- 

 fused, sometimes evanescent ; perithecia often gregarious in floc- 

 cose patches, but sometimes scattered, 85-145 fi in diameter, 

 rarely reaching to 180 //, globose-depressed, cells 10-15 fi wide; 

 appendages 7-28, 2)^-8 times the diameter of the perithecium, 

 usually narrow (about 5 n wide), more or less flexuose-contorted 

 angularly bent, and nodulose, but sometimes wider and not an- 

 gularly bent, always very flexuose, colorless, thin-walled above, 

 becoming thick-walled in the lower half, aseptate, sometimes 

 slightly rough, apex 3-4 times dichotomously branched, branching 

 very irregular and lax, branches strongly flexuose, often more or 

 less curled, lips of ultimate branches strai^^ht or recurved ; asci 



