AN UNDESCRIBED SPECIES OF GYMNOSPORANGIUM 
FROM JAPAN 
By W. H. Long, 
Forest Pathologist , Investigations in Forest Pathology , Bureau of Plant Industry 
INTRODUCTION 
In the Annual Report of the Connecticut Agricultural Experiment Sta¬ 
tion for 1912 (pt. 5, p. 350), Dr. Clinton reports the introduction of 
Gymnosporangium japonicum Syd. on Juniperus chinensis. The rust was 
found on both stems and leaves of a form known as J. compacta , while on 
a seedling of /. chinensis called J. virginalis the rust occurred only on 
the leaves. The plants showing rust only on the leaves were planted in 
an isolated place. The following spring they were found to be free from 
rust. 
Through the kindness of Dr. Perley Spaulding the writer was able to 
examine some of the infected material from Dr. Clinton's herbarium 
containing both types of the rust. The rust on the woody stems seems 
to be Gymnosporangium japonicum Syd., but that on the leaves or young 
twigs differs in most of its microscopic and macroscopic characters from 
G. japonicum . According to the report, the rust on the leaves or young 
twigs is apparently an annual, while the other, G. japonicum , is a perennial; 
one is found on the leaves and green twigs, the other on the woody stems; 
one causes no deformation of the host, the other produces fusiform 
enlargements 4 cm. in length or longer. The microscopic characters of 
the two differ as widely as the gross characters mentioned above. 
The writer has found in most species of Gymnosporangium three types 
of teliospores in the same sorus. One type has very thick colored walls; 
one, moderately thick colored walls; and the third, thin and colorless 
walls. These three types usually differ from each other also in shape 
and size of the spore as a whole or in the individual cells of each spore. 
Constant specific characters may occur in one type, often in the thin 
colorless-walled spores, while they are absent in the other two types or 
are not so pronounced. For this reason the characters of at least the 
two extreme types of spores should be given for each species under dis¬ 
cussion. In the following descriptions the two extreme types are fully 
described for two of the species and the three types for the third one. As 
a matter of convenience in comparing the three species brief descriptions 
of G. japonicum and G. haraeanum are also given. 
( 353 ) Vol.I, No. 4 
Jan. 10,1914 
G—11 
Journal of Agricultural Research, 
Bept. of Agriculture, Washington, D, C. 
