192 A Monograph of the Ervsiphaceae 



line, densely interwoven ; asci very numerous, from 20 to 34, or 

 more, large, broadly ovate-oblong to subcylindrical or subpyri- 

 form, 70-100, usually about 85, x 30-36 /i, usually stalked; 

 spores 4-6, 20-22 X 10-12 fJL. 



Host, — Bio-dovia oraveokiis and var. albican lis. 



.^u.^v.v. . 



Distribution.— ^OKTH America : United States ; — Montana, 



Wyoming, Colorado, L 



Two forms of ErysipJie occur on species of Bigclovia {B. grave - 

 olois) and its var. albicaulis^ and B, viscidiflora {B, Douglasii) in the 

 United States. The ErysipJic on B. viscidiflora has regularly bi- 

 sporous asci, and although a marked form from its large size must 

 be referred to E, ciclwraccantin, as has already been done by Ameri- 

 can mycologists. The Erysiphc on B. gravcolcns is ver}^ different. 

 The perithecia, which occur in scattered patches on the stem, are 

 at first more or less immersed and firmly imbedded in the pannose 

 tomentum of the host-plant; at maturity, however, the perithecia 

 break through the tomentum of the stem, and appear in naked 

 black patches. The perithecia are, as a rule, very large, and con- 

 tains a great number of asci. The asci are lar<je. rather irregular in 



^V-, i*.*^XiV-i »* * V-j_j 



shape, sometimes subcylindrical or somewhat pyriform, and con- 

 tain constantly 4-6 spores, are about 22x11 fi in size. These 

 characters give the plant, in my opinion, a position somewhat in- 

 termediate between E. polygouid^nd E. aggrcgata ; from the former 

 it differs in the larger size, and larger and more numerous asci, 

 from the latter in the more interwoven appendages and 4-6 longer 

 spores. American mycologists have placed this form in E. cicho- 

 raccarum, merely for the reason, it appears that, as mentioned 

 above, on another species of Bigclovia {B. viscidiflora), E. cichora- 

 ceartim^ with its normal bisporous asci, is found. We must re- 

 member, however, that many cases occur in which distinct species 

 of the Erysiphaceae are found on even the same species of host- 

 plant, and very commonly we find two or more species of mildew 

 on different species of host-plants belonging to the same genus. 



The name E. sepulta was published in the Bot Gazette, 14 : 

 286. 1S89, as follows : '' Erysiphc scpidta Ell. & Everh. n. sp. 

 This species is so named only provisionally, and may yet prove to 

 be only an old species under peculiar circumstances. . . It comes 

 so near to E. cichoraccarum that it may well be doubted if it be a 

 new species ; but the perithecia appear imbedded in the woolly 



