186 BOTANICAL GAZETTE [MARCH 
but occasionally with a septum near the base, seated on a pseudo- 
parenchymatous hymenial base which is colorless, 10-15 X 2-3 yp, 
terminating rather abruptly at the apex in a sterigma-like projec- 
tion on which the spores are borne; conidia hyaline, one-celled, 
straight, rounded at both ends, oblong-cylindrical, ovate, elliptical, 
or even pyriform, 8-10 X3-3.5 wp. 
’ Habitat on living leaves of Ulmus americana. Oconomowoc, Wisconsin, 
August 22, 1919. Type specimen deposited in the herbarium of the Univer- 
sity of Illinois. This species differs from Gloeosporium ulmeum in the shape 
and appearance of the spots, in the fact that it is not associated with a peri- 
thecial stage as that fungus constantly is, in the absence of a black basal 
stroma, and in the larger spores. In external appearance the two forms are 
quite distinct. It differs also from Gloeosporium inconspicuum Cav. and 
G. inconspicuum Cav. var. campestris Dor. in the character and appearance 
of the spot and in the much larger spores. 
Principal European leaf spot 
SySTREMMA ULM (Schleich.) Thiess. and Syd.— The leaf spot of 
the elm occurring in Europe on Ulmus campestris, U. effusa, and 
U. glabra has a somewhat superficial resemblance to that pro- 
duced in this country by Gnomonia ulmea (Schw.) Thiim. This 
may readily be seen by comparing fig. 6, which shows the European 
spot on a leaf of Ulmus campestris, with figs. 4 and 5, which are 
leaves of U. americana affected by the Guomonia. The two diseases 
have been much confused in this country, and it has been quite 
common for American plant pathologists and mycologists to speak 
of the latter fungus under the name of the European organism. 
In examining specimens of the Gnomonia spot in various collec- 
tions in this country, I have found it quite as often referred to in 
this manner as under its true name or synonyms. ‘There are two 
references in literature to the occurrence of the disease caused by 
Systremma Ulmi in America, in addition to various others which 
are clearly due to a confusion of the two forms. One of these 
cases is in the report by TRELEASE (40) of the presence in Wisconsin 
of Phyllachora Ulmi Fuck., which name is a synonym of Sys- 
trenmma Ulmi. On examination of the specimen, which is in the 
museum of the Shaw Botanical Gardens at St. Louis, Missouri, it 
was found that the disease was the American form, caused by 
