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IOWA ACADEMY OF SCIENCE 
pendages 4-22, 2% -8 times the diameter of the perithecium, delicate, hyaline 
or occasionally brown at the base, apex 2-4 times dichotomously branched, 
branches variable; tips rectirved ; asci 2-16, 45-72x28-38 micra, spores 4-6, 
18-22x10-13 micra. 
On Catalpa catalpa (L.), Karst, Johnson Co., Sept. 25, 1886 (Macbride). 
On Catalpa speciosa Warder. Decatur Co., 1904 and 1905 (Anderson) ; *Iowa 
City, Oct., 1886 (Hitchcock); Scott Co., Sept. 1, 1897 (Macbride). 
This species is occasionally quite destructive, causing a dying and 
premature dropping of the leaves, thereby greatly weakening the 
tree. 
3. Microsphaera alni extensa (Cooke & Peck) Salmon. 
Microsphaera extensa Cooke & Peck. Bessey, The Erysiphei, and Prel. List 
Ames Flora; Hitchcock, Partial List Iowa Powdery Mildews. 
Microsphaera quercina (Schwein.), Burr, in part. Fink, Blights, etc., of Fay- 
ette. 
Epiphyllous; mycelium persistent; perithecia gregarious, 90-140 micra in 
diameter, cells 10-20 micra wide; appendages 8-19, 214-6 times the diameter of 
the perithecium, apex 3-5 times dichotomously forked; tips regularly recurved; 
asci 3-8, short pedicellate, 58-72x34-45 micra; spores, 4-8, 22-26x12-15 micra. 
On Quercus alba L. *Fayette, 1893 (Fink). 
On Quercus prinoides Willd. Decatur Co., .Oct., 1904 (Anderson) . 
On Quercus rubra L. * Fayette, 1893 (Fink). 
This variety seems to intergrade with the type of the species and 
it is difficult to draw the line between them. Some of the specimens 
on Quercus referred to under M. alni may belong here and the two 
specimens from Fayette referred to here may belong under M. alni. 
Forms on Q. rubra from Decatur County are clearly M. alni while 
specimens on Q. prinoides gathered about the same time are typical 
of the variety extensa. It is not very destructive. 
4. Microsphaera grossulariae (Wallr.) Lev. 
Microsphaera grossulariae (Wallr.), Lev. Bessey, The Erysiphei; Fink, 
Blights, etc., of Fayette. 
Microsphaera van bruntae Ger. Bessey, The Erysiphei. 
Epiphyllous or amphigenous; mycelium evanescent or subpersistent, peri- 
thecia scattered to densely gregarious, 65-130 micra in diameter, cells 14-20 
micra wide; appendages 5-22, 1-1% times the diameter of the perithecium, 
colorless, apex 4-5 times closely dichotomously branched, ultimate branches 
forming a narrow fork, tips not recurved; asci 4-10, very short stalked, 46-62x 
28-38 micra; spores 4-6; very rarely only 3, 20-28x2-16 micra. 
On Sambucus canadensis L. Fayette, Oct., 1893 (Fink) ; Johnson Co., Oct., 
1889 (Linder). 
In Europe this species attacks the cultivated gooseberry and is 
sometimes quite troublesome. In America it sometimes attacks 
