106 
IOWA ACADEMY OF SCIENCES 
Economic Considekations. This fungus was so abundant along Birch 
Creek that the vitality of the trees was seriously impaired, as a dozen or 
more of the “witches’ brcom.s” might occur on a single tree. The writer 
has also observed its destructive work along the branches of Cache La 
Poudre river in the hicdicine Bov/ Mountains. 
Exonscus cerasi (FuckeP) Sadebeck. 
PIiSTOEY. Tnis species was described by Fuckel and has been referred 
to by American authors as Exoascus loiesnerr. It was described under 
the latter name by Rathay"^ and distributed by Ellis and Everhart* in 
North American Fungi. 
This fungus has also been referred to as Taphrina deformans by Rob- 
inson® and as Exoascus deformans by Saccardo; SadebeclP, however, in 
1893, referred it to Fuckel's Ex. cerasi. 
General Characters. Infected leaves assume a dark color, become 
very much curled and somewhat puffed, twisted and -wrinkled as in the 
peach leaf curl; and the branches of diseased trees are somewhat dis- 
torted, but in the western type, hexenbesen do not appear as in the 
European E. cerasi and as reported by Farlowh 
Microscopic Characters. The mycelium is perennial in the buds and 
in the spring penetrates the tissues of the young leaves and develops on 
the lower surface in the shape of a subcuticular hymenium. The asci are 
extremely variable, but usually club shaped, rounded at the top and 
slender varying in size from 7-10" x 30-50". The stalk cells are from 5-8" 
X 10-16". There are eight ascospores which are aspherical or ellipsoidal, 
usually ellipsoidal. Mrs. Patterson'-’ has the following interesting note on 
specimens examined during her study of the North American Exoasceae. 
“I have examined it upon the leaves of Prunus serotina collected at 
Cambridge, Mass., by Dr. W. G. Farlow and Economic Fungi No. 1^8 
from Alabama, and also upon deformed leaves of “cultivated cherry”, 
{Prunus avium?) distributed as No. 2286 of Ellis, North American Fungi. 
I think to this species can be referred specimens of Prunus americana 
showing both branch and leaf distortion; some were collected in Illinois 
by Prof. Li. H. Bailey, and several were sent me by Prof. L. H. Pammel, 
which had been found in various localities in Iowa. I am also indebted 
to Prof. Pammel for the opportunity of examining Prunus Tiortulana col- 
lected near Cedar Rapids, Iowa, by A. B. Dennis, and leaves of the Miner 
plum, a cultivated variety of P. Jiortulana. collected at Amana, Iowa, by 
A. Noe, both of wiiich are doubtless affected by this species. It is also 
found upon several specimens of Prunus pennsylvanica from New Hamp- 
shire. I believe it proper to refer to this species the disease of Prunus 
1. 8ymb. Myc. 252 as a var. of E. deformans. Fung.* Rli. 2275. 
2. Farlow. Proc. Soc. Prom. Agrl. Sci. 7 : 25. 
R. Oesterr. Dot. Zeit. 80 : 225. 
4. No. 2285 b. 228G. See also Krieger Fun Sax. 621. Von Tbum. Myc. 
Univ. 2265. 
5. Annals of Bot. 1 : 168. 
6. Syll. Fung. 8: 817. 
7. 1. c. 
8. Proc. Am. Acad. 18: 84. Proc. Soc. Prom. Agrl. Sci. 7. 25: See, also 
Tubeuf I’flanzenk. 181. 
, 9. Bull. Lab. Nat. Hist. 3. 3: 104. 
