1902] BRIEFER ARTICLES 65 
associated does not occur frequently, although more often than the 
uninitiated might suppose. A clue of less value may be obtained by 
nding a limited area monopolized by a single species of grass or 
sedge, the whole well rusted. We now search for aecidia upon herbs, 
shrubs, or trees growing within the rusted area, or not to exceed a 
hundred feet from it. Abundance and nearness, and taking into 
account all other forms, give us our clue. This was the kind of clue 
used for the sowing of Sambucus. A Carex of very distinctive habit, 
species unknown as the plants were sterile, grew in a thick mass, not 
over ten feet across, that was heavily rusted each season. This spot 
had been under observation a number of years. No other locality in 
the immediate region was known for the Carex, and owing to the char- 
acter of the surrounding ground, it could scarcely find a foothold 
within a half mile, or possibly much more. No aecidia appeared on 
any plant growing among the Carex, or within ten feet of it. It was 
a rich region for plant rusts, and within one hundred feet aecidia were 
found upon Ranunculus, Oenothera, Impatiens, Eupatorium, Napaea, 
Sambucus, Ptelea, and Urtica. The aecidia of Ptelea and Urtica were 
known to belong to other teleutospores ; the aecidia on Ranunculus and 
Oenothera were too abundant and widely diffused through the adjoin- 
ing region to warrant their being considered. This left four kinds of 
accidia sufficiently local to be accepted for trial, and after two season’s 
work it has been positively ascertained that this particular Carex rust 
_ ‘Must belong to the aeecidium on Sambucus. 
\a rust occurs very sparingly in a region, but richly developed, 
: or when it is restricted to a rare host, close watch in the immediate _ 
: — 1s sometimes rewarded by the discovery of the alternate form. 
= Uccasionally this alternate form is so conspicuous that it has been pre- 
Wiously collected, but not infrequently it t proves to be a sort not before 
= ed for the district. 
- 2 The better one becomes acquainted with the rusts of a small region, @ 
re chances there are that his inferences a crgtos epee 
the test 
d host ¢ of the aecidia, and grass or sedge leaves bear- 
latter gathered during the previous winter and subse- 
of 
e at out of doors. Both are — st hs mail a ata — : 
