202 A Monograph of the Erysiphaceae 



ever, have proved on examination to be Spliacrothcca huniuli, var. 

 fuligiiica, and there seems reason to doubt if E. cichoraccariim has 

 really ever occurred on Taraxacum, 



In the case of the species which occurs commonly (in the coni- 

 dial condition) on the leav^es of Cjiaums and Ciiciirbita in cultiva- 

 tion, the determination has apparently been equally unsatisfactory. 

 Nearly all mycologists {e.g,^ Leveille, Fuckel, Jaczwski, Passerini, 

 etc.), refer the fungus to Spliacrothcca Castagnci ; Schroeter, 

 however, places it under E. polygenic and records the finding of spec- 

 imens with perithecia on Cucnrbita Pcpo. The perithecial stage of 

 this fungus on Ctictirbita and Cticwnis is evidently rare, and in all the 

 herbarium specimens and those in exsiccati (all named Sphacro- 

 tJicca Castagnci) examined I have found only the conidial stage. I 

 have, however, collected specimens on Cucnrbita Pcpo, at Reigate, 

 Surrey, England, in 1898, with a few perithecia, and the fungus here 

 was undoubtedly E. cichoraccariim, the asci being regularly 2- 

 spored. It is interesting to note that a few American authors have 



similarly determined the fungus ; c. g., Humphrey (169) records E. 

 cichoraccarum on cucumber [Qicuinis). It is, of course, possible 

 that more that one species of ErysipJu occurs on these host-plants, 

 but in the present case it seems more probable that the fungus has 

 been constantly named Spliacrothcca Castagnci merely because 

 this species was originally recorded on these host-plants, and it 

 would be very interesting to know if any example with perithecia 

 of Spliacrothcca really exists. 



The Erysiphc on Valeriana officinalis has been referred without 

 exception (by Fuckel, Magnus, Karsten, Schroeter, etc.) to E. 

 polygoni, but all the specimens I have seen so named, have proved 

 on examination to be E. cichoraccaruni. On the other hand, the 

 Erysiphc which occurs on thistles has been referred entirely to 

 E. cichoraccarum, while, as a matter of fact, on the stems of 

 C7iicits lance olatiis, etc., an interesting form of E. polygoni oc- 

 curs not uncommonly. Similarly, the Erysiphc on Anchusa and 

 Echium has been referred to E. cichoraccarum, but' all the speci- 

 mens I have seen so named in exsiccati, etc., prove to be E. poly- 

 gojii. The fungus on Cnicus criophonis (in Montagne's herbarium) 

 referred to E. taurica by Leveille (214) is E. cichoraccarum. The 

 Erysiphc on species of Galium, which has hitherto been referred to 



