272 BOTANICAL GAZETTE [ APRIL 
this -spring near Lafayette, Ind., upon Ulmaria rubra (Spirea 
lobata); in the bright red coma stage. Feeling at first uncer- 
tain of the identity of the rust, the caoma spores were sown 
upon the Ulmaria, and also upon Salix, Convolvulus, and Ipomea, , 
with the result that it grew only upon Ulmaria, producing at first 
uredospores and afterward teleutospores. An after-sowing of 
uredospores upon Ulmaria gave a crop of more uredospores. The 
dates are as follows: 
May 17, Czomospores sown on Ulmaria rubra, May 30, uredo; July — 
teleutospores, 
May 17, Czomospores sown on Salix longifolia ; no infection. 
May 23, Ceomospores sown on Convolvulus sepium ; no infection. 
May 24, Ceomospores sown on /fomea pandurata ; no infection. 
June 16, Uredospores sown on U/maria rubra, July —, uredospores. 
7. PucciniA AMERICANA Lagh. 
This grass rust on various species of Andropogon is very 
common throughout North America, but has been generally con- 
founded with Puccinia Andropogi Schw., which has the same range 
and affects the same hosts. The teleutospores are barely distin- 
guishable, but the uredospores are entirely unlike those of 
P. Americana, being large and thin walled, those of P. Andropogt 
small and thick walled. The detection of the zcidium is due 
to the careful observation of Mr. William Stuart, who noticed 
that plants of Pentstemon pubescens, growing near Andropogon 
bearing teleutospores of the previous year, were well covered 
with xcidia (Acidium Pentstemonis Schw.), while the same SP& 
cies in other localities was quite free. With this hint sowings 
were undertaken. Teleutospores from Andropogon scoparius were 
sown on Pentstemon pubescens and ecidia appeared in great abun- 
dance and vigor; zxcidiospores were sown on Andropogon and 
large, thin-walled, brown uredospores appeared. The results 
were ample and complete, and were further emphasized by 
similar results subsequently obtained by Mr. Stuart. The dates 
are as follows : 
May 3, Teleutospores from Andropogon scoparius sown on Pentstemow 
pubescens ; May 11, spermogonia ; May 20, zcidia. 
