206 
Mycologia 
termined, as oospores are present in abundance. They very evi- 
dently belong to a species of Peronospora, rather than to a Chytri- 
diaceous fungus. They are yellowish-brown, quite large, measur- 
ing 60-95 P across, and have a conspicuously wrinkled epispore. 
Peronospora Phlogina Dietel & Holway, Bot. Gaz. 
19: 306. 1894 
Two species of Peronospora have been described from hosts of 
the family Polemoniaceae. The first of these, P. Phlogina, was 
described from material collected by Professor Holway at Deco- 
rah, Iowa, on Phlox divaricata. The next year P. Giliae Ellis & 
Ev. 13 was described from northern Idaho on an undetermined 
species of Gilia. Such is the uncertainty of matters taxonomic 
that the host is no longer considered to belong to that genus, but 
to one of the recent segregates, fit accordingly bears the name 
Microsteris gracilis (Dough) Greene. While the two species of 
fungi have found their way into separate sections of the genus 
Peronospora in Berlese’s monograph they agree in all essential 
details. The conidiophores are of the same type, the conidia 
present less variation than do those of some species of the genus, 
and all together there does not appear to be more variation than 
can reasonably be expected in a species, especially one so poorly 
known. These species, therefore, must be united under the older 
name. 
Peronospora Potentillae De Bary, and its segregates 
While various species of Peronospora have been described on 
widely separated genera of Rosaceae they have, with the excep- 
tion of P. sparsa Berk, on species of Rosa, at one time or another 
been referred to P. Potentillae. Three of these species are present 
in America, and it is with these that we are at present concerned. 
Peronospora Potentillae De Bary, the older of these species, was 
originally described from material on a species of Potentilla. As 
further collections were made it was found to be prevalent on sev- 
eral other genera of herbaceous Rosaceae. Later two French 
botanists, Roze and Cornu, described Peronospora Fragaricc , 14 
13 Cont. U. S. Nat. Herb. 3: 276. 1895. 
11 Bull. Soc. Bot. France 23: 242. 1876. 
