INFLUENCE OF THE HOST ON THE MORPHOLOGICAL 
CHARACTERS OF PUCCINIA ELLISIANA AND PUCCI- 
NIA ANDROPOGONIS 
By W. H. Long, 
Forest Pathologist , Investigations in Forest Pathology , Bureau of Plant Industry 
Both Puccinia ellisiana Thuem. and Puccinia andropogonis Schw. 
have their telial stage on various species of Andropogon. For its aerial 
stage Puccinia ellisiana goes to certain species of Viola, while a number 
of species of Pentstemon are the aerial host for Puccinia andropogonis . 
Two years ago the author 1 called attention to the fact that Puccinia 
ellisiana might have its aerial stage on Pentstemon as well as on certain 
species of Viola. 
Culture data obtained in 1913 proved that this supposition was cor¬ 
rect, as both Viola and Pentstemon were infected with Puccinia ellisiana . 
The changes produced in the morphological characters of the uredinio- 
spores when this rust was carried over to Pentstemon were so radical 
that the writer would not publish these culture data until they had 
been tested by another year's work. During the season of 1914, there¬ 
fore, special attention was given to the infection of species of Viola 
and Pentstemon with Puccinia ellisiana and the infection of Pentstemon 
and Viola with Puccinia andropogonis . The culture work of 1914 
agreed absolutely with the results obtained in 1913. 
The remarkable feature of the results obtained was not the infection 
of two widely separated hosts by the same rust, but the changes pro¬ 
duced in the morphology of the urediniospores of Puccinia ellisiana 
after passing through Pentstemon as the aerial host. The urediniospores 
of Puccinia ellisiana have thick verrucose walls, while those of Puccinia 
andropogonis have thin, echinulate walls. It is mainly on these well- 
marked and constant differences in the urediniospores that the two spe¬ 
cies are distinguished from each other. When urediniospores are not 
present in the teliosporic material the two rusts are often separated by 
determining by cultures which is the aerial host, Viola or Pentstemon, of 
the specimen in hand. 
CULTURE DATA FOR 1913 
DISSEMINATION OF PUCCINIA ELLISIANA AND PUCCINIA ANDROPOGONIS 
The aeciospores and urediniospores of both Puccinia andropogonis and 
Puccinia ellisiana are not carried far by wind currents. Six feet is the 
extreme distance yet observed by the writer for the spread of viable 
spores of either species to near-by stools of Andropogon. 
1 Long, W. H. Notes on three species of rusts on Andropogon. Phytopathology, v, 2, p. 164-171, 
August, 1912. 
Journal of Agricultural Research, 
Dept, of Agriculture, Washington, D. C. 
47531 14—5 
Vol. II, No. 4 
July 15, 1914 
G—27 
(303) 
