Some factors influencing the prevalence of Endothia gyrosa 
NEIL E. STEVENS 
(WITH FIVE TEXT FIGURES) 
INTRODUCTION 
The distribution of the American species of Endothia does not 
coincide with that of their hosts. Range maps of these species 
made by Dr. C. L. Shear and the writer as the result of two years 
collecting, show that Endothia gyrosa (Schw.) Fries is abundant in 
the Southeastern States and has been found occasionally as far 
north as southern Connecticut and western New York, while two 
of its hosts, Fagus and Quercus, occur several hundred miles further 
north. Endothia fluens (Sow.) S. & S., which is common on 
Castanea and Quercus from northern Alabama to southern Penn- 
sylvania, has not yet been found north of this region. The 
territory between Virginia and southern New England appears 
then to be a transition region for these fungi. Examination of 
these maps also shows that Endothia singularis (H. & P. Syd.) 
S. & S. and E. fluens occupy fairly well defined climatic areas and 
are apparently not found in America outside these areas. Endothia 
gyrosa, however, while abundant only in the Southeastern States, 
has been found in Connecticut, New York, Kansas, Texas, and 
on the Pacific Coast. 
The present paper deals with Endothia gyrosa, which has a 
much wider known range in America than any other species of 
the genus. This fungus is undoubtedly indigenous, having first 
been collected by Schweinitz at Salem, North Carolina, nearly a 
century ago, and previous to recent work had been collected at 
various times in the following widely separated localities: Indiana, 
1831 (?), Schweinitz; Texas, 1869, Ravenel; New York, 1872, G. W. 
Clinton; Florida, 1886-87, Calkins; Mississippi, 1887, Earle; 
Kansas, 1887, Swingle; Louisiana, 1887, Langlois; New Jersey, 
1892 (?), Ellis. 
The intensive collecting of the last few years has not greatly 
