KUNKEL: ORANGE RUSTS OF RUBUS 567 
rusts and it is not possible in any given case to determine with 
certainty which rust was collected. Since Gymnoconia occurs 
on Rubus saxatilis and R. arcticus in Europe it seems natural to 
assume that the Caeoma on related species in this country belongs 
to Gymnoconia. It is probable, therefore, that the orange rust 
on the low-growing R. arcticus L. of Yukon, R. stellatus Smith of 
Alaska, and R. triflorus Richardson or R. americanus Britton of 
New Hampshire and Wisconsin will prove to be Gymnoconia. 
The writer has collected Gymnoconia on R. frondosus Bigel., R. 
canadensis L. and R. nigrobaccus Bailey. These are all upright- 
growing species and it may be that the orange rust on many of the 
other upright species is Gymnoconia. The writer feels inclined 
to think, however, that Caeoma nitens is the more common of 
the two rusts and that it will prove to have a wider range of host 
species than Gymnoconia. According to Clinton (3) the Caeoma 
has been reported from Carolina, Connecticut, Georgia, Illinois, 
Iowa, Kansas, Maryland, Massachusetts, Minnesota, Mississippi, 
Missouri, Nebraska, New Hampshire, New Jersey, New York, 
Ohio, Pennsylvania, Texas, West Virginia and Wisconsin while 
the teleuto-stage is reported from only four states: Illinois, Massa- 
chusetts, Missouri and New York. The orange rust in most of 
those states where the teleuto-stage has not been found is probably 
Caeoma nitens. New Hampshire, however, must be mentioned 
as an exception, since the rust common in that state has proven 
to be Gymnoconia. The fact that the orange rust is much more 
conspicuous than the teleuto-stage may to some extent account 
for its being more often reported. Only a careful study of the 
distribution and host limitations of the two forms in the several 
states can furnish grounds for definite conclusions. Nevertheless 
we may predict that the orange rust reported on R. cuneifolius 
Pursh, R. occidentalis L., R. Randii (Bailey) Rydb., R. strigosus 
Michx., R. trivialis Michx., R. villosus Ait., R. vermontanus Blanch. 
and R, vitifolius Cham. & Schlecht. is Caeoma nitens. 
So far as is at present known the short-cycled orange rust 
does not occur in Europe. Before accepting this conclusion, 
however, a careful study of the manner of germination of the 
aecidiospores from various localities should be made. Special 
attention should be given to the Caeoma in those sections where 
