334 
JAMES R. WEIR AND ERNEST E. HUBERT 
uredinia upon the rosettes which continue living until spring. The 
rust is carried over principally by means of urediniospores which 
reinfect the leaves of the rosette and continue throughout the year 
infecting the leaves of the flowering stalk during the spring and 
summer. The fact that this form of the rust on E. adenocaulon 
produces no telia is evidence of its continuation in the uredinial stage 
and also explains the absence of a corresponding aecial stage upon 
Abies. 
P. pustulatum occurring upon E. angustifolium produces telia 
which are capable of infecting species of Abies. This plant develops 
from perennial horizontal root stalks. Rosettes which overwinter 
are not produced and no evidence has been found to indicate any 
stage of the rust overwintering on the living plant. 
Studies have also been made upon Coleosporium solidaginis (Schw.) 
Thum. occurring upon species of Aster and Solidago. 
On October i8 four pots containing rosettes of Aster spp., 2 of 
Aster conspicuus Lindl. and 2 oi A. laevis-gayeri Grey, infected with 
the uredinial stage of C. solidaginis, were placed in the greenhouse at 
Missoula, Mont. All of the leaves of the rosettes were removed and 
the chances for infection depended entirely upon such few uredinio- 
spores as had become transferred from the infected leaves. The rust 
had been mature for some time previous to placing in the greenhouse. 
On October 28, uredinia appeared on such leaves or portions of leaves 
as were then present. From this date on other leaves as they appeared 
became infected and developed scattered groups of uredinia. Four 
control plants remained normal. Collections of this stage of the rust 
upon species of Aster and Solidago have been made during the months 
of the year when only the rosettes of the plants were in evidence. 
Most of these collections were made in late winter or in early spring 
before the snow had left the ground. Mains^^ in his article on the 
overwintering of Coleosporium solidaginis produces very good evidence 
of the overwintering habit of this rust on rosettes of Solidago sp. The 
collections in Idaho and Montana of infected rosettes of Solidago 
missouriensis Nutt. and S. canadensis L. during the months of March 
and April before the peridia of the aecial stage on Pinus contorta have 
appeared confirms the conclusions of Mains as to the wintering habit 
of this fungus. 
12 Mains, E. B. The Wintering of Coleosporium solidaginis. Phytopathology 
6:371. 1916. 
