266 Wisconsin Academy of Sciences, Arts, and Letters. 
ably on Cirsium muticum than on any other of the hosts. It is 
sometimes very abundant on cultivated Tragopogon. 
Phytophthora thalictri Wilson & Davis. This occurs throughout 
the state and is collected every year. There are no collections on 
Thalictrum dioicum. As T. revolutum occurs in but the south¬ 
eastern corner of the state T. dasycarpum is the usual host, 
Phytophthora infestans (Mont.) DBy. In Wisconsin, as else¬ 
where, there is wide fluctuation in the frequency and abundance 
of this parasite. 
Premia lactucae Eegel. Frequent and abundant, especially on 
Lactuca spicata. It has not been collected often on cultivated 
lettuce in the open but is often abundant under glass. 
Plasmopara humuli Miyabe & Takahashi. In southeastern and 
southwestern Wisconsin. A scanty development has been seen 
also in central Wisconsin. It appears to be indigenous. It was 
collected at Caryville in the Chippewa valley in July, 1920, with 
oospores. 
Plasmopara pygmaea (Unger) Schroet. Frequent and abundant 
on Hepatica and Anemone quinquefolia. The var. fusca (Pk.) 
Davis has been collected in southern Wisconsin and on Hepatica 
only. This form is peculiar in not developing conidia. 
Plasmopara ribicola Schroet. Although some of the hosts occur 
throughout the state this has been observed in the northern part 
of the state only, the southernmost localities being in Shawano 
county. Within its range it is not infrequent and fairly abundant 
on the hosts of northern range Bibes prostratum and B. triste. 
Plasmopara geranii (Pk.) Berk & DeToni. Widely distributed 
on Geranium maculatum. 
Plasmopara obducens Schroet. Frequent throughout the state 
in spring, less so in summer when it is more often found north¬ 
ward. 
Plasmopara acalyphae Wilson. This has been found only at a 
station near Madison and in very small quantity at Caryville. It 
is inconspicuous and as a rule very few conidiophores are de¬ 
veloped. [Since collected at Arena and at Lone Rock and a trace 
at Oconto.] 
