THE AECIAL STAGE OF COLEOSPORIUM 
RIBICOLA 
W. H. Long 
On a recent field trip to Bear Canyon, located in the Sandia 
Mountains about twelve miles from Albuquerque, New Mexico, 
the writer found a Peridermium on the needles of pinon {Finns 
edulis). The infected pinons were growing in close proximity 
to Ribes leptanthum, which is rather common near the bottoms of 
canyons. Several days later, a trip was made to Tejano Canyon, 
about twenty-eight miles from Albuquerque, where the Perider- 
mium was again found on pinon in close association with Ribes 
plants. 
Inoculations under control conditions were made on two spe- 
cies of Ribes from both of the collections. Sowings of aecio- 
spores from the Bear Canyon material (F.P. 21164) were made 
April 29 on Ribes leptanthum and R. longifolium. On May 16 
the uredinia of a Coleosporium appeared on the lower surface of 
the leaves of R. leptanthum (theR. longifolium plants which were 
inoculated damped off). Sowings of the aeciospores from the 
Tejano Canyon material (F.P. 21165) were made May 3 on R. 
leptanthum and R. longifolium. Uredinia appeared May 18 on 
the lower side of the leaves of both of the species of Ribes inocu- 
lated. The control plants of each set of inoculations remained 
free from the rust. 
The Coleosporium obtained by inoculating the Ribes plants 
with the aeciospores of the Peridermium from pinon proved to 
be identical in all its characters with Coleosporium ribicola (E. 
& E.) Arthur. This infection of the Ribes leaves by the pinon 
Peridermium, thereby producing the typical uredinia of C. ribi- 
cola, proves that this Peridermium is the aecial stage of C. ribi- 
cola and should be called Peridermium ribicola. 
A technical description of the aecial stage of this fungus is 
given below. 
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