Witson: NortH AMERICAN PERONOSPORALES 69 
Aecidium Ipomeae Schwein.; Berk. Grevilléa 3: 60. 1874. 
(Hyponym.) 
Cystopus Convolvulacearum Otth; Zalew. Bot. Cent. 15: 223. 
1883. 
Cystopus Convolvulacearum Speg. Ann. Soc. Ci. Argent. 17: 128. 
1884. 
Cystopus Ipomoeae-panduranae Stev. & Swing. Trans. Kan. Acad. 
Sci. 11: 67. 18809. 
Sori amphigenous or caulicolous, white or light-yellow, promi- 
nent, superficial, o.5—-20 mm., rounded, often confluent and fre- 
quently producing marked distortions of the host ; conidiophores 
hyaline, clavate, unequally curved at base, about I5x 30 #; 
conidia short-cylindric, similar or the terminal more rounded, hya- 
line; the membrane with an equatorial thickening, usually very 
Pronounced, 14~20 x 12-18 #4; odsporic sori separate from the 
conidial, caulicolous, rarely on the petioles, 1-2 x 5-6 cm. or even 
more, causing marked distortion of the host; odspores light yel- 
lowish-brown, 25-55 #4; epispore papillate or with irregular, more 
or less curved ridges. 
The position in the genus of this species has varied quite a 
little in the various elaborations which have appeared in recent 
years. Berlese and De-Toni * included it in Cystopus Tragopo- 
fonts from which it was separated by Saccardo.f According to 
Zalewski (2. c.) and Fischer t it is placed next to A. candida, in the 
first instance on account of the structure of the epispore of the 
06spore, and in the second as the result of inaccurate observations 
as to the thickness of the conidial membrane. In his Monografia 
delle Peronosporacee, Berlese attempts to accommodate the species 
to this varied treatment and so places C. /pomoeae-panduranae 
next to C. candida on account of its conidial membrane having no 
quatorial thickening, and includes C. Convolvulacearum Speg. 
among those species which have an equatorially thickened coni- 
dial membrane, and at the same time cites various species of Con- 
volvulaceae as hosts of C. Ti ragopogonis. An examination of 
Co-type material of Spegazzini’s species leaves no doubt concern- 
ing its identity with the North American species. Three packets 
of the material distributed by Ellis and Everhart in their North 
tit ie, EE Oy a 
* Saccardo, Syil, Fung. 7: 234. 1888. 
t Syll. Fung. 9: 340. 1891. : 
TRabenh. Krypt. Fl. ed. 2. 4!: 419. 1892. 
