328 
JAMES R. WEIR AND ERNEST E. HUBERT 
fern hosts. The variations in the spore markings are neghgible. In 
view of the results secured by Fraser and the determinations by 
Arthur, it is suggested that these five species be combined under the 
name of one species of Uredinopsis. The aecial stages of all five 
species have been found to be identical with Peridermium halsameum 
and the close similarity of P. pseudo-halsameum (D. & H.) Arth. with 
P. halsameum has led us to consider them here as one species, namely, 
Peridermium halsameum. The differences in the description of the 
two species do not seem to be of sufficient importance to continue their 
separation. The description given by Arthur and Kern^ give a 
slightly larger spore for P. halsameum and no mention is made of the 
color of the spores of P. pseudo-halsameum which are colorless as in the 
other species. The peridia of both are fairly long (0.75-1 mm.) and 
with the colorless spores furnish excellent means of identification. All 
stages of this rust should therefore be referred to one species of Ure- 
dinopsis. The aecial stage was not only found in abundance this 
season on Ahies grandis but also on A. lasiocarpa. This fungus has 
been collected in the Northwest in 1896 under the name of P. pseudo- 
halsameum (D. & H.) Arth. Hedgcock^ reports P. pseudo-halsameum 
on Ahies grandis, A. lasiocarpa, and A. nohilis in 1912. In a recent 
article by Schmitz^ a claim is made to the first collection of the fungus 
west of the Mississippi Valley. A glance at the literature^ will show 
that Peridermium halsameum was collected on Ahies grandis on the 
slope of Mt. Paddo, Wash., by W. N. Suksdorf in October, 1903. 
P. halsameum was collected on Ahies grandis in California in 1896. 
Many other collections of this fungus have been made since then and 
the collections of this laboratory at Missoula show considerable 
material (eight collections) from the northwestern states collected 
during the years 191 1 to 1916. 
Uredinopsis pteridis 
During the past two seasons a very interesting Peridermium has 
been collected on the needles of Ahies grandis (fig. i). This fungus is 
^Arthur, J. C, and Kern, F. D. Uredinales. N. Amer. Flora 7: 115. 1907. 
^ Hedgcock, G. G. Notes on Some Western Uredineae Which Attack Forest 
Trees. Mycologia 4: 141. 1912. 
^ Schmitz, H. Preliminary Note on the Occurrence of Perider?nium halsameum 
in Washington. Phytopathology 6: 369. 191 6. 
^Arthur, J. C., and Kern, F. D. North American Species of Peridermium. 
Bull. Torrey Club 33 : 403. 1906. 
