TRbooora 
JOURNAL OF 
THE NEW ENGLAND BOTANICAL CLUB 
Vol. 22. April, 1920. No. 256. 
EUPATORIUM PURPUREUM AND ITS ALLIES. 
K. M. WIEGAND. 
Tue verticillate-leaved Eupatoriums have long given trouble to 
American botanists. In connection with work on the flora of Central 
New York, the writer has found it necessary to make some dispo- 
sition of the material ordinarily recognized as Eupatorium purpureum. 
That more than one form is to be found under this name in New York 
State has been apparent for some time, but the limits and characters 
of these forms did not seem to agree with those recognized by various 
authors as delimiting the numerous subdivisions of this species. 
The problem was taken, with others, to the Gray Herbarium, where 
Dr. Robinson kindly placed at the writer's disposal the very complete 
collection of E. purpureum in that institution, and also photographs 
made by him of Linnean and Willdenovian specimens in European 
herbaria. This material was supplemented by the rich collection 
of New England Eupatoriums in the herbarium of the New England 
Botanical Club, and of New York State plants of this group in the 
herbarium of the New York State College of Agriculture. As a 
result of this study, a treatment has been worked out which it is 
hoped will aid in clearing up the difficulties that have so long sur- 
rounded this section of Eupatorium. 
Briefly stated, four species have been confused under the general 
name E. purpureum L. For clearness, these may be numbered, and 
their most striking characters listed, as follows: 
1. Florets 6-9, rarely 5-12: stem speckled: leaves usually in 3's 
or 4’s, ovate, abruptly contracted at the base, more or less plainly 
