412 Witson: Nortu AMERICAN PERONOSPORALES 
has since been borne out by an examination of authentic material 
of the earlier species. The present species is easily distinguished 
from either of the two preceding ones by its larger conidia and 
more complexly branched conidiophores. 
On ASCLEPIADACEAE: 
Vincetortcum fursutum (Michx.) Britton, Alabama, Carver 
932. (Type of Plasmopara Vincetoatci.) 
Vincetoxicum suberosum (L.) Britton, Florida, McCulloch. 
An additional host, V. gonocarpos Walt., is also recorded. 
Type LocaLity: Blufton, South Carolina, on Gonolobus sp. 
(= Vincetoxicum hirsutum (Michx.) Britton). ° 
Distripution: Maryland to Florida and Mississippi. 
5. PSEUDOPERONOSPORA Rostew. Ann. Inst. Agron. 
Moscou g: 47. Ja 1903. — Flora 92: 422. O 1903 
Plasmopara § Peronoplasmopara Berl. Riv. Pat. Veg. g: 122. 
19Ol. 
Peronoplasmopara Clinton, Rep. Conn. State Agr. Exp. Sta. 
29: 234. 1905. . 
Mycelium intracellular, branching, haustoria small, usually 
simple ; conidiophores pseudo-monopodially branched, the pri- 
mary branches arising, as a rule, at acute angles, the ultimate 
branchlets acute ; conidia typically colored, rarely hyaline, elliptic 
in outline, _conspiciously papillate both apically and_ basally ; 
oospores thin-walled, smooth or roughened ; odgone thin-walled. 
Type species, Peronospora cubensis B. & C. 
The present genus is the most anomalous of the tribe, com- 
bining as it does certain characteristics of the present and suc- 
ceeding tribes. The conidia germinate, as in all species of the 
_ Rysotheceae, by zodspores, while the colored conidia suggest a 
close relationship with Peronospora. This is further augmented 
by the apically acute conidiophores, the method of branching of 
which is intermediate between the typical method of the two 
tribes in question. 
The close relationship of the two species to each other and 
their problematical taxonomic position was pointed out by Waite 
at the time he described the second one.* He, however, allowed 
them to remain in the genus Peronospora. The next step was 
* Jour. Myc. 7: 105. 1892. 
We a 
