Occurrence of the pycnial stage of Puccinia Taraxaci* 
Louise DospALL 
On April 29, 1920, dandelions were found on University Farm, 
St. Paul, heavily infected with rust. In addition to the fact that 
this was the earliest date on record at the University of the 
occurrence of Puccinia Taraxaci (Rabent.) Plow., this collection 
was of particular interest because pycnia were found accompany- 
ing the uredinia. As far as could be discovered from the lit- 
erature, this stage had never before been collected in North 
America, although both Plowright (1889) and Grove (1913) 
had reported its occurrence in England, and Jacky (1909) in 
Germany. 
In the spring of 1921 a careful watch was kept for the first 
appearance of dandelion rust to determine whether or not the 
pycnial stage was common in this region. The first pycnia 
were found on University Farm, April 17, 1921. Subsequently 
they were found in various localities around St. Paul and Minn- 
eapolis. If a careful search was made, the pycnial stage could 
be found in almost any cluster of plants. A difference was 
noted in the abundance of the rust during the two seasons in 
which observations were made. In 1920 the pycnia were found 
accidentally in two localities. In both cases the infection on 
the plants was so conspicuous that the rust was observed while 
one was walking hurriedly through the field. In 1921 no pycnia 
could be found without the most diligent search. 
Through correspondence with Dr. H. S. Jackson, it was 
learned that the pycnial stage of Puccinia Taraxaci had been 
collected at Brookville, Indiana, in April, 1918, by C. A. Ludwig, 
and the specimens deposited in the Arthur Herbarium. This 
specimen was compared with the Minnesota collection and the 
rusts found to be identical. In spite of the fact that collections 
are rare, it would seem that the occurrence of the pycnial stage 
must be rather common. 
The pycnia of Puccinia Taraxaci are amphigenous on yellow, 
slightly swollen spots, which occur frequently along the midrib 
*Published, with the approval of the Director, as Paper No. 303 of the 
Journal Series of the Minnesota Agricultural Experiment Station. 
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