THE FUNGI WHICH CAUSE PLANT DISEASE 185 



to similarity of habit and the frequent abnormal development 

 of the appendages, so that the published references are not always 

 reliable. 



Microsphsera L6viell6 (p. 175) 



Perithecia globose to subglobose; asci several, 2 to 8-spored-, 

 appendages not interwoven with the mycelium, branched in a 

 definite manner at the apex, usually dichotomously and often 

 very ornately, rarely undivided or merely once dichotomous. 



According to Salmon there are thirteen species; Engler and 

 Prantl ' recognize thirty. 



M. grossiilarise (Wal.) L6v. 



Epiphyllous or amphigenous; mycelium evanescent or sub- 

 persistent; perithecia scattered or densely aggregated, globose- 

 depressed, 65-130 n; cells 14-20 n; 

 appendages 5-22, colorless, 1-1 M 

 times the diameter of the perithe- 

 cium, 4 to 6-times closely dichoto- 

 mously branched, branches of first 

 and second order very short, all pjo. i35._m. grossuiarise, append- 

 segments deeply divided, tips not age tips. After Salmon. 



recurved; asci 4-10, broadly ovate or oblong, usually with a very 

 short stalk, 46-62 x 28-38 n; spores 4-6, rarely 3, 20-28 x 

 12-16 fi. 



On five species of Bibes and two of Sambucus. This is the 

 common European gooseberry-mildew, which is not common in 

 America except on the elder. 



M. berberidis (D. C.) L6v. occurs on the barberry in Europe 

 and Asia. 



M. alni (Wal.) Salm. 



Amphigenous; mycelium evanescent or persistent; perithecia 

 scattered to gregarious, globose-depressed, very variable in size, 

 usually small, 66-110 n, or even up to 135 m; cells 10-15 n 

 wide; appendages variable in number (4-26) and length, Vs to 

 2}4 times the diameter of the perithecium, more or less rigid, 

 colorless throughout or amber-brown at base, apex variously 



