112 A Monograph of the Erysiphaceae 



more numerous, and always stouter and wider (5—7 fJ. wide). 

 Moreover, in most perithecia of U, gcnicidata at least one or two 

 of the appendages show an abrupt geniculate bend, and this char- 

 acter, when present, is quite sufficient to distinguish the present 

 plant from all the species of Uncimtia except some forms of U. 

 salu'is, van Mijabci, and from this variety U, genicidata differs in 

 the much narrower appendages, not enlarged upwards. Some- 

 times, however, all the appendages are straight, and U. genicidata 

 is then best known by the rather few, delicate, narrow append- 

 ages. The asci are described as being 6-spored, but they are fre- 

 quently 4-spored. The fewer and much longer appendages at 

 once separate the present plant from U, parvida, 



U, genicidata is confined to the United States ; the record by 

 Issatchenko (171) of its occurrence in Russia rests on an error. 



Among the specimens of Erysiphaceae sent to me from the 

 Herbarium of the U. S. Department of Agriculture was one labelled 

 '' Eiysiphe cichoraccaruni DC. On Hydrophylhini appcndicnlatum, 

 Crawfordsville, Indiana. E. M. Fisher, Oct., 1890. No. 1003." 

 This specimen showed, on examination, only perithecia of a species 

 of Uiicimda scattered irregularly over the surface of the leaf 

 Feeling doubtful if this Uncimda really originated on this host- 

 plant, I wrote to Professor Galloway on the subject, who replied, 

 '' I regret to state that we are unable to give you any information- 

 in regard to the care of the material labelled E, cichoraccaruni on 

 HydropJiylliun appcJidicuIatnnL It has for some years been in 

 mycological envelopes, labelled as above, and whether it was previ- 

 ously in contact with any host bearing Uncimda^ it is now impossi- 

 ble to ascertain. Nothing but perithecia of Uncimda appear to be 

 upon several specimens examined to-day, and we are fearful that 

 the first determination was an error.'' After a careful comparison 

 of the perithecia, I found them to agree in all characters with those 

 of the present species — U, genicidata — which has been recorded 

 only on Morns rubra. The leaves of the Hydrophylluni show 

 patches of mycelium on the upper surface, and on these as well as 

 on parts of the leaf without mycelium, the perithecia of U, genic- 

 idata are scattered. These perithecia appear more or less loose, 

 and can be easily lifted off with a needle, and I was not able to 

 observe any connection with the mycelium, nor the occurrence of 



