1888. | BOTANICAL GAZETTE. 53 
There is, perhaps, no better way of treating the subject 
than that of taking up the species of the group, one by one, 
in the order in which they are given in Dr. Farlow’s paper 
upon the ‘‘ Enumeration of the Peronosporee of the United 
States,’ which was published in the GAzETrE for November, 
1883, and to which additions were made in March, 1884. 
Phytophthora infestans DBy. No signs of this rot of the 
potato have been observed the past season. Two years ago 
was an average one, and there were many complaints from 
all parts of the state. More than half of the potatoes in 
there was very much less, and this season there has been 
entire freedom from the disease in this locality. 
Peronospora Halstedii Farl. is the most common species 
of this vicinity. Its hosts are numerous, the leading ones of 
Which are several species of Helianthus, Silphium, Eupa- 
torium and Bidens, and a very long list of other genera, all 
of the order Composite. Last season Helianthus grosse- 
serratus was added to the host list of this vicinity, and this 
Season Bidens connata var. comosa was found infested. 
any time. Last season it was only moderately common, but 
oy e 
hibited a rank growth of succulent herbage. 
Peronospora obducens Sch. upon Impatiens fulva, although 
