IOWA ACADEMY OF SCIENCE 
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Erysiphe martii Lev. Bessey, the Erysiphei, and Prel. List Ames Flora. 
Hitchcock, Partial List Iowa Powdery Mildews. 
Erysiphe tortilis (Wallr.), Fr. Bessey, Prel. List Ames Flora. Hitchcock, 
Partial List Iowa Powdery Mildews. 
Amphigenous; mycelium variable, thin, effused or abundant, persistent or 
evanescent; perithecia gregarious or scattered, 5-180 micra, usually about 90 
micra in diameter, cells 10-15 micra wide; appendages very variable in number 
and length, %-20 times the diameter of the perithecium, usually interwoven 
with the mycelium, colored at the base or throughout or rarely hyaline or 
white; asci 2-8, rarely mayn. 46-72x30-45 micra; spores 3-8, 19-25x9-14 micra. 
On Anemone canadensis L. Iowa City, X (X). 
On Anemone sp. Ames, 1894 (Carver). 
On Anemone virginiana L. Ames, July 12, 1876 (Bessey). 
On Astragalus carolinianus L. Ames, Sept. 9, 1894 (Combs) ; *Belle Plaine, 
Sept., 1886 (Hitchcock) ; Decatur Co., Sept., 1904, and Aug. and Sept., 
1905 (Anderson) ; Decorah, Aug. 2, 1886 (Holway) ; Fayette, Sept., 1893 
(Fink) . 
On Brassica nigra (L.) Koch. Fremont Co., Aug. 8, 1905 (Anderson). 
On Clematis virginiana L. Ames, Oct., 1882 (Bessey), *Aug., 1886 (Hitch- 
cock) ; Decatur Co., Sept., 1904 (Anderson) ; Iowa City, Oct. 10, 1886 
(Macbride), Oct. 7, 1900 (Bloom). Oct., 1900 (Stromsten). 
On Falcata pitcheri (T. & G.), Kunze, Decatur Co., Oct., 1905 (Anderson). 
On Geranium maculatum L. Iowa City, Oct. 2 (Bloom). 
On Onagra biennis (L.) Scop. Fayette, 1893 (Fink) ; Decorah, Sept. 17, 1879 
(Holway) . 
On Pisum sativum L. Ames X (X) ; Decatur Co., June, 1905 (Anderson) ; 
Iowa City, May, 1886 (Macbride). 
On Polygonum aviculare L, Ames, June 29, 1905 (Anderson) ; Decatur Co., 
July, 1904 and 1905 (Anderson). 
On Polygonum erectum L. Decatur Co., July 12, 1905 (Anderson) ; Ring- 
gold Co., Oct. 7, 1905 (Anderson). 
On Polygonum ramosissimum , Michx. Fremont Co., Aug. 8, 1905 (Ander- 
son) . 
On Ranunculus abortivus L. Ames, X (Rolfs) ; Decatur Co., July, 1904 and 
1905 (Anderson) ; Iowa City, July, 1886 (Macbride). 
On Syndesman thalictroides (L.), Hoffman, Iowa City, May, 1889 (Linder). 
On Thalictrum purpurascens L. Decatur Co., July 12, 1905 (Anderson). 
This is the most variable of our species of Erysiphaceae. Were 
it not that the character of the various extreme types intergrade 
into each other we would be inclined to consider various types as 
specifically distinct. Our specimens on Polygonum have appendages 
only V 2 -IV 2 times the diameter of the perithecium while on Clematis 
they sometimes reach a length of 15-20 times the diameter of the 
perithecium. Other Ranunculaceae show forms with appendages 
of intermediate length. Other characters also vary widely. In 
Decatur County Onagra biennis and Syndesmon thalictroides are 
