230 A Monograph of the Erysiphaceae 



the variations that occur are never important enough to make us 

 doubt that we are deahng with one cosmopoHtan species, able to 

 hve not only on a great number of different trees, but also, ap- 

 parently, on some herbs (see list of host-plants above). 



I have united P. Candollcl Lev., P. antarctica Speg., and P. 

 bcrbcridis Palla with the present species. 



Leveille described P. CandoUci from specimens occurring on 

 the leaves of a species of Nyssa in North America, and remarked 

 (214, p. 150), "Cetteespeceressemble a la precedente \P. corylca\\ 

 la seule difference repose dans les sporanges, qui sont au nombre 



de huit et qui renferment quatre spores au lieu de deux." I have 



examined two specimens of Lcveille's plant ; one in Berkeley's 

 Herbarium at Kew, the other in Montague's Herbarium In the 

 Paris Museum; both specimens are named in Leveille's handwriting. 

 Many of the asci in these specimens were found to be 2-spored 

 (in one perithecium all the asci were bisporous), but most con- 

 tained 3 spores ; I did not observe 4 spores in any. The asci 

 were frequently above 8 in number, in one case being as numerous 

 as 18 ; this character, however, is not important, as there are often 

 less than 8 asci in undoubted examples of P. corylea. The two 

 examples showed no other differences, and there is therefore no 

 reason to consider " /". CandoUci" as more than a mere form of 



A 



P. corylea with frequently 3 (or even, perhaps, sometimes 4) spores 

 in the ascus. It is curious that Phyllactinia has not been reported 

 on Nyssa since Leveille's time. The specimen on which Berkeley's 

 record of " P. CandoUci;' from Canada (Foe), in Grevillea, 4 : 158. 

 I S76, was based, agrees in every way with P. corylea. 



I have not been able to see a specimen of P. antarctica Speg., 

 found on Ribcs MagcUanicum in Patagonia, but from the description 

 given have no hesitation in referring it to P. corylea. Spegazzini 

 records: "P. snffulta (Reb.) Sacc. \P. corylea-] as occurring on 

 Anarthrophyllnm rigidum from the same region, and gives a good 

 description of the fungus. Speggazzini's diagnosis of P. antarctica, 

 however, applies better to the more usual form of P. corylea than 

 does his diagnosis of the form of " P. suffidta " mentioned above, 



and there can be no doubt that both specimens are referable to P. 

 corylea. 



P. bcrbcridis Palla is a very interesting form. In Palla's valu- 



