Sphaerotheca 45 



terwoven with the myceUum, simple or' vaguely branched ; fre- 

 quently obsolete. Etym. Oifaipa, spliacra, and dy:r^, thcca. 



Distribution, — Europe, Africa, Asia, Australia, North and South 

 America — 5 species and i variety. 



The single ascus and floccose appendages, more or less re- 

 sembling the mycelial hyphae, separate Sphaerotheca from all other 

 genera. The most interesting features shown are the production 

 of special thick-walled, interlaced hyphae from the vegetative 

 mycelium, forming a persistent pannose covering for the more or 

 less immersed perithecia (5. pannosa, S. lancstris, etc.) and the 

 complete separation of the inner wall of the perithecium from the 



^phila 



tris\ S, pliytoptophila 



iopt, 



Key to tUe Species of »pliaerotUeca 



. Mycelium persistent, thick, pannose, forming dense patches composed of special hy- 

 phae, in which the perithecia are more or less immersed. 2, 

 Mycelium without these characters. ^' 



. Persistent mycelium usually satiny and shining, white, sometimes becoming gray or 

 pale brown. 

 Persistent mycelium dark brown. 



3. Inner %v'all of perithecium separating from the outer, hyphae of persistent mycelium 



A. Ian est ns. 



2. pannosa. 



3. 



very tortuous. 



— J -V -i-TJ- ^ ^ ^—^ -1 r ^mr^^a^ ■ 



Inner w^all not separating, hyphae straighter 



•^ 



4. ianestris* 

 mors-uvae. 



60^78 

 separating from the outer. 



5. phytoptophila. 



separating Irom the outer. ^- r j £ ^ 



Perithecia 50-120 /. In diameter, ascus 45-90 X 50-7^/^ ; inner wall scarcely sepa- 



_.i: 5- 



rating. 



5. Cells of outer wall of perithecium IO-20 « wide, averaging 15 !>■■ ^- '''"''^"^'• 



Cells 20-30 (rarely 40) ft wide, averaging 25 f^- ^- ^'""'"^'' ^■^'■M^'"'^"- 



I. Sphaerotheca humuli (DC.) Burr. [Figs. ii6, 117] 



Miicor Erysiphe Linn. Sp. PL 2 : 1186 (partim). i753- 

 Sclerotium Erysiphe Pers. Obs. Myc. 1:13 (partim). 1796 I 



Pers. Syn. Fung. 124 (partim). 1801. 



Erysiphe hnmuli DC. Fl.Fr. 6: 106. 181 5 ; Duby, Bot. Gall. 

 2:868. 1830; Tul. Sel. Fung. Carp, i : 21 1. //. 7. / 9- 1S61. 



K sanguisorbae DC. Fl. Fr. 6: loS. 1815 ; Duby, Bot. Gall. 

 2 : ^ib"^. 1830. 



