236 "A Monograph of the Erysiphaceae 



think that the latter sprang from, the organic base of the perithe- 

 ciuni, whereas as Dr. Neger (/. c) has shown^ the perithecium, 



when so fixed, is really turned upside down. Neger has briefly 

 mentioned that in a Phyllactinia from the Argentine examined by 

 him the outgrowths wxre characterized by a much-branched stalk- 

 cell, and on this account the author regards the fungus as a new 

 species of Pliyllactinia, and proposes the name P, clavariaefonnis. 

 As a full description and figures of the plant are promised, the 

 question of its specific distinctness must be left open until these 

 appear, although as I have already pointed out (314, p. 453./. j) 

 the validity. of the character relied upon seems doubtful. 



Richon (298) describes a fungus which attacks the leaves and 

 stems of Poa nemoralis and Fcstiica sylvatica, and gives the name 

 '' Erysiphe graminis ? DC/' to the plant, but remarks: *' Les 

 perithcces soul ornes de 6 ou 8 appendices, simples et renflcs a la 

 base. II constitue probablement une variete de PhyUactinia suf- 

 fiilta non signalee par les auteurs et differente de V Erysiphc gram- 

 inis de Saccardo/' It will be well to ascertain if the Phyllactinia 

 was actually growing on the plants mentioned, before adding 

 grasses to the list of the host-plants of the species. 



P. corylea is sometimes mentioned among the diseases attack- 

 ing cultivated nut trees, but I have found no statement that it has 

 ever caused any serious injury. Pammel (268, p. 103) mentions 



\\\7\X Phyllactinia '' occurred destructively on Fraxinus;' at Ames, 

 Iowa. 



Doubtful or Excluded Species 



Erysiphe radiosum Fr. Obs. Myc. I : 207. 1815 = Actino- 

 ftenia fosae (Lib.) Fr. 



E, album Fr, /. r. No specimen seen. 



Alphitomorpha rosanim Wallr. Ann. Wett. Ges. 4 : 238. 

 1S19. No specimen seen. Wallroth gave the following descrip- 

 tion : '* A subiculo subtilissimo fere obsoleto, sporangiis parvis 

 sparsis sphaericis, capillitio obsoleto. Hypophylla in Rosa cinna^ 

 momea^ rarior. Species ob minutiem sporangiorum facile praeter- 

 videnda, nee quoque subiculo detegenda, quod cum tomento folii 

 obductum est Dubiam igitur modo indico." In Fl. Crypt. 

 Germ. 2: 755. 1833. Wallroth placed it as a variety under 

 '' A. pcnicillatar 



