IOWA ACADEMY OF SCIENCE 
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same species on certain hosts shows a tendency to form lobed 
haustoria. 
4. Erysiphe graminis DC. 
Erysiphe graminis DC. Bessey, Prel. List Ames Flora; Hitchcock; partial 
list Iowa Powdery Mildews; Fink, Blights, etc., of Fayette. 
Usually epiphyllous; mycelium more or less persistent; perithecia large, 
135-280 micra in diameter, scattered or gregarious, more or less immersed in the 
persistent mycelium, cells obscure; appendages rudimentary, very short, pale 
brown; asci 9-30, pedicellate, 70-108x24-40 micra; spores 8 (rarely 4) ; 20-23x 
10-13 micra, seldom produced on the living host plant. 
On Cinna arundinacea, L. Fayette, 1893 (Fink). 
On Poa pratensis , L. *Ames, Aug., 1886 (Hitchcock) ; Decatur Co., Oct. 4, 
1904 (Anderson) ; *Fayette, 1893 (Fink) ; Johnson Co., May 3, 1894 (X). 
This species is quite common on Poa pratensis, but the perithecia are sel- 
dom found. They appear to be formed early. 
Erysiphe taurica Lev. 
Mycelium often covering the whole plant, usually persistent, effused, dense- 
ly compacted, tomentose, membranaceous or crustaceous; perithecia usually im- 
mersed in the persistent mycelium, large, 135-240 micra in diameter, soon be- 
coming concave; cells obscure; appendages usually numerous, densely inter- 
woven, rather short and vaguely branched, sometimes very short or even 
obsolete; asci 7-38, pedicellate, large, 75-110x28-40 micra; spores 2, large, 
28-40x14-22 micra. 
On Heliopsis scabra Dunal. Decatur Co., Aug.-Oct., 1904 and 1905 (Ander- 
son) ; Ringgold Co., Oct. 10, 1905 (Anderson). 
Heretofore this has been considered as an old world species. 
Salmon, in his monograph of the Erysiphaceae, gives the distribu- 
tion of this species as the continent of Europe (France, Spain, Italy, 
Greece, Germany, Austria-Hungary, Russia), Algeria in Africa, 
and Turkey, Syria, Persia, Turkestan, and India in Asia. It seems 
somewhat strange that this species should now be found in the 
middle of the United States, but I can refer the form under consid- 
eration to no other species as it agrees in every important detail 
with the description given for E. taurica. 
In August, 1904, I first collected this species but on examination 
I found that the perithecia had not developed asci. I collected at 
intervals during the fall but not until very late in the season could 
I find traces of asci. In 1905 I found asci somewhat earlier but 
have been unable to find spores without soaking in water for 24-48 
hours. 
During the autumns of 1904 and 1905 nearly every plant of 
Heliopsis scabra seen by the writer in Decatur and Ringgold 
counties, Iowa, and Harrison County, Missouri, presented a white 
