Sept, a, i$i 8 
PiUon Blister-Rust 
413 
eased with the secial form, then past maturity. Old aeciespores were 
found to be present by Messrs. Hedgcock and Bethel. This tree was 
examined by Messrs. Bethel and Hunt in May, 1918, but new, fresh 
secia had not been formed. Old aeciospores were still present. Messrs. 
Hedgcock and Bethel collected specimens of the Cronartium sp. at sev¬ 
eral points around Prescott during the latter part of October, 1917, and 
pronounced it distinct from C. ribicola , but identical with the species of 
Cronartium previously found at Bayfield and other localities in Colorado. 
DESCRIPTION OF THE FUNGUS 
The morphology of this new species of Peridermium differs so much 
from that of P. strobi Kleb., the secial stage of Cronartium ribicola , that 
the writers are led to believe it is the secial stage of a distinct species. 
The Colorado species of Cronartium on Ribes spp. is here designated 
“ Cronartium occidentale ” with the following description: 
Cronartium occidentale, n. sp. (PI. 54, 56, 57). 
O—Pycnia caulicolous, scattered, forming blisters 0.5 cm. or more in diameter; . 
exudate orange-chrome; 1 pycniospores hyalin, pyriform or obovoid to ellipsoid, 2 to 
3 by 3 to 5 averaging 2 by 4 m: pycnial scars seldom found (PI. 56). 
I. —Mcia caulicolous, sometimes causing slight hypertrophy; secial cavities 
large, often entirely hidden by the bark; peridia inconspicuous, thin, evanescent, 
only slightly protruding, if at all, rupturing at irregular cracks in the bark or near 
the top if protruding; peridial cells variable, nearly smooth on outer surface, verru- 
cose on inner surface, 12 to 26 by 17 to 36 jx, averaging 19 by 25 n, walls 1 to 5 fx thick; 
aeciospores variable, usually obovoid to ellipsoid, 12 to 28 by 22 to 38 fx, walls colorless, 
1 to 5 m thick, averaging 3 jn, outer wall coarsely verrucose, with deciduous tubercules, 
which in end view are 0.7 to 2.5 by 1 to 4.6 n, averaging 1.4 by 1.8 in side view 1.7 
to 4.2 fx, averaging 2.7 m long (PI. 54). 
In Arizona on Pinus monophylla. 
~ In Colorado on Pinus edulis . 
The type specimen of the secial stage is FP 26227 2 * * * on Pinus edulis t collected by 
Messrs. E. Bethel and H. L. Gaymon at Bayfield, Colo., on July 13, 1917. 
II. —Uredinia hypophyllous, rarely amphigenous, scattered on irregularly-rounded 
areas; sori light yellow to yellow, pustular, 0.2 to 2 mm. in diameter, dehiscent by 
a central opening; urediniospores 13.5 to 20 by 18.5 to 32 fx, averaging 16 by 24 
with colorless walls 2 to 3 u thick, sharply echinulate on outer surface. 
III. —Telial columns hypophyllous or rarely amphigenous, and occasionally on the 
petioles and peduncles, cylindrical or nearly so, 60 to 170 fx thick, up to 4 mm. long, 
walnut-brown to Vandyke-brown; teliospores oblong to cylindric, 9 to 19 by 27 to 
56 m; wall nearly colorless, 0.4 to 2 \x thick (PI. 57). 
In Arizona on Ribes aureum, R. odoratum, and Grossularia reclinataXG . hiriella. 8 
In Colorado on Ribes aureum, R. inebrians, and Grossularia leptantha. 
In Washington, D. C., by cultures on Ribes americanum t R. aureum t R. coloradense, 
R. giraldi , R. glandulosum , R. malvaceum , R. nigrum , R. odoratum , R. sanguineum, 
R„ sp., Grossularia inermis , G. missouriensis, and G. reclinataXG . hirtella. 
1 Color terms used are from Ridgway, Robert, color standards and color nomenclature. 43 
P*» 53 pl. (col.). Washington, 1912. 
2 The type specimens of Cronartium occidentale are deposited in the Pathological Collections of the'United 
States Department of Agriculture at Washington, D. C. 
* The type specimen of the uredinial and telial stages is FP 24420 on Ribes aureum collected by Messrs. 
Bethel and Hunt at Bayfield, Colo., on September 15, 1917. 
