^^ A Monograph of the Erysiphaceae 



certain resemblance to U. salids, from which it is distinct in its 

 large size, usually 8-spored asci, and thick-walled appendages ; 

 sometimes many of the appendages are bifid, when an approacli is 

 made towards the type. In U. aceris, however, although simple 

 appendages do occur, these are always very {^\n in number, and 

 rarely, if ever, as numerous as in the var. Tiilasnci (see, however, 

 note above). Moreover, the densely compacted persistent my- 

 celium is never found in U. aceris t}^pe. 



Fuckel first separated the present plant as a distinct species 

 {U. Tulasnci), ^nd gave in the diagnosis the character " conidiis 

 concatenatis, perfecte globosis, 8 mik. diametr." Subsequent 

 authors have repeated the statement, and have relied on this 

 character as the chief one for separating the plant. Thus Saccardo 

 (307) says of U. Tiilasnci, " Praecipue habitu et conidiis globosis 

 dignoscenda species," and Winter (394, p. 42), <' Unterscheidet 

 sich von a. aceris hauptsachlich durch die kugeligen Conidicn, die 

 bei jener, wie bei alien anderen Unciiuila arten elliptisch sind.'' 



Eriksson (119, //. ^. / 10-12) figures these small globular 

 conidia, and contrasts them with the much larger conidia of U. 

 aceris proper. 



Examination of herbarium material makes me doubt whether 

 authors have been right in regarding these bodies as the conidia of 

 the present plant. In certain specimens I have found, on the same 

 leaf, the two kinds of conidia represented in Figs. 90-92. Fig. 

 90 is evidently the form described by the above authors (cf " Eriks- 

 son's figures) ; the conidiophores are very small, and with the small 

 more or less globose spores (about 8 fi in diameter) bear no re- 

 semblance to the Oidiuiii-ioxm of other members of the Erysi- 

 phaceae. The other form (Fig. 91), present in about equal num- 

 bers agrees closely with the figures of the conidia and conidiophores 

 of U. aceris given by Eriksson (loc. cit.,/ 7, 8). It is possible that 

 the small form is some species of Oospora associated accidentally 

 with the Uncimda. 



The mycelial characters, which give the present plant so differ- 

 ent an appearance from the type, we know to be of very slight 

 systematic value (cf. remarks on ^^Erysiphe dcnsa Berk)," and 

 other characters seem hardly important enough to give a 'higher 

 than varietal rank under U. aceris. 



